2018
- Order from chaos: Observation of large-scale flow from turbulence in a two-dimensional superfluid,
S. P. Johnstone, A. J. Groszek, P. T. Starkey, C. J. Billington, T. P. Simula, and K. Helmerson.
[arXiv] [Bibtex] [Abstract]
Interacting systems driven far from equilibrium tend to evolve to steady states exhibiting large-scale structure and order. In two-dimensional turbulent flow the seemingly random swirling motion of a fluid can evolve towards persistent large-scale vortices. Lars Onsager proposed a model based on statistical mechanics of quantized vortices to explain such behavior. Here we report the first experimental confirmation of Onsager’s model of turbulence. We drag a grid barrier through an oblate superfluid Bose–Einstein condensate to generate non-equilibrium distributions of vortices. We observe an inverse energy cascade driven by the evaporative heating of vortices, leading to steady-state configurations characterized by negative temperatures. Our results open a pathway for quantitative studies of emergent structures in interacting quantum systems driven far from equilibrium.
@article{johnstone_order_2018, title = {Order from chaos: Observation of large-scale flow from turbulence in a two-dimensional superfluid}, url = {http://arxiv.org/abs/1801.06952}, abstract = {Interacting systems driven far from equilibrium tend to evolve to steady states exhibiting large-scale structure and order. In two-dimensional turbulent flow the seemingly random swirling motion of a fluid can evolve towards persistent large-scale vortices. Lars Onsager proposed a model based on statistical mechanics of quantized vortices to explain such behavior. Here we report the first experimental confirmation of Onsager's model of turbulence. We drag a grid barrier through an oblate superfluid Bose--Einstein condensate to generate non-equilibrium distributions of vortices. We observe an inverse energy cascade driven by the evaporative heating of vortices, leading to steady-state configurations characterized by negative temperatures. Our results open a pathway for quantitative studies of emergent structures in interacting quantum systems driven far from equilibrium.}, urldate = {2018-01-23TZ}, journal = {arXiv:1801.06952 [cond-mat, physics:physics]}, author = {Johnstone, Shaun P. and Groszek, Andrew J. and Starkey, Philip T. and Billington, Christopher J. and Simula, Tapio P. and Helmerson, Kristian}, month = jan, year = {2018}, eprint = {1801.06952}, keywords = {Condensed Matter - Quantum Gases, Physics - Fluid Dynamics} }
- Continuously observing a dynamically decoupled spin-1 quantum gas,
R. P. Anderson, M. J. Kewming, and L. D. Turner.
Physical Review A 97, 13408 (2018).
[arXiv] [DOI] [Bibtex] [Abstract]
We continuously observe dynamical decoupling in a spin-1 quantum gas using a weak optical measurement of spin precession. Continuous dynamical decoupling modifies the character and energy spectrum of spin states to render them insensitive to parasitic fluctuations. Continuous observation measures this new spectrum in a single preparation of the quantum gas. The measured time series contains seven tones, which spectrogram analysis parses as splittings, coherences, and coupling strengths between the decoupled states in real time. With this we locate a regime where a transition between two states is decoupled from magnetic-field instabilities up to fourth order, complementary to a parallel work at higher fields [D. Trypogeorgos et al., preceding paper, Phys. Rev. A 97, 013407 (2018)]. The decoupled microscale quantum gas offers magnetic sensitivity in a tunable band, persistent over many milliseconds: the length scales, frequencies, and durations relevant to many applications, including sensing biomagnetic phenomena such as neural spike trains.
@article{anderson_continuously_2018, title = {Continuously observing a dynamically decoupled spin-1 quantum gas}, volume = {97}, url = {https://link.aps.org/doi/10.1103/PhysRevA.97.013408}, doi = {10.1103/PhysRevA.97.013408}, abstract = {We continuously observe dynamical decoupling in a spin-1 quantum gas using a weak optical measurement of spin precession. Continuous dynamical decoupling modifies the character and energy spectrum of spin states to render them insensitive to parasitic fluctuations. Continuous observation measures this new spectrum in a single preparation of the quantum gas. The measured time series contains seven tones, which spectrogram analysis parses as splittings, coherences, and coupling strengths between the decoupled states in real time. With this we locate a regime where a transition between two states is decoupled from magnetic-field instabilities up to fourth order, complementary to a parallel work at higher fields [D. Trypogeorgos et al., preceding paper, Phys. Rev. A 97, 013407 (2018)]. The decoupled microscale quantum gas offers magnetic sensitivity in a tunable band, persistent over many milliseconds: the length scales, frequencies, and durations relevant to many applications, including sensing biomagnetic phenomena such as neural spike trains.}, number = {1}, urldate = {2018-03-14TZ}, journal = {Physical Review A}, author = {Anderson, R. P. and Kewming, M. J. and Turner, L. D.}, month = jan, year = {2018}, eprint = {1706.08322}, pages = {013408} }
2017
- Continuous Faraday measurement of spin precession without light shifts,
M. Jasperse, M. J. Kewming, S. N. Fischer, P. Pakkiam, R. P. Anderson, and L. D. Turner.
Physical Review A 96, 63402 (2017).
[arXiv] [DOI] [Bibtex] [Abstract]
We describe a dispersive Faraday optical probe of atomic spin which performs a weak measurement of spin projection of a quantum gas continuously for more than one second. To date, focusing bright far-off-resonance probes onto quantum gases has proved invasive due to strong scalar and vector light shifts exerting dipole and Stern-Gerlach forces. We show that tuning the probe near the magic-zero wavelength at 790 nm between the fine-structure doublet of 87Rb cancels the scalar light shift, and careful control of polarization eliminates the vector light shift. Faraday rotations due to each fine-structure line reinforce at this wavelength, enhancing the signal-to-noise ratio for a fixed rate of probe-induced decoherence. Using this minimally invasive spin probe, we perform microscale atomic magnetometry at high temporal resolution. Spectrogram analysis of the Larmor precession signal of a single spinor Bose-Einstein condensate measures a time-varying magnetic field strength with 1 μG accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at 10pT/√Hz sensitivity.
@article{jasperse_continuous_2017, title = {Continuous Faraday measurement of spin precession without light shifts}, volume = {96}, url = {https://link.aps.org/doi/10.1103/PhysRevA.96.063402}, doi = {10.1103/PhysRevA.96.063402}, abstract = {We describe a dispersive Faraday optical probe of atomic spin which performs a weak measurement of spin projection of a quantum gas continuously for more than one second. To date, focusing bright far-off-resonance probes onto quantum gases has proved invasive due to strong scalar and vector light shifts exerting dipole and Stern-Gerlach forces. We show that tuning the probe near the magic-zero wavelength at 790 nm between the fine-structure doublet of 87Rb cancels the scalar light shift, and careful control of polarization eliminates the vector light shift. Faraday rotations due to each fine-structure line reinforce at this wavelength, enhancing the signal-to-noise ratio for a fixed rate of probe-induced decoherence. Using this minimally invasive spin probe, we perform microscale atomic magnetometry at high temporal resolution. Spectrogram analysis of the Larmor precession signal of a single spinor Bose-Einstein condensate measures a time-varying magnetic field strength with 1 μG accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at 10pT/√Hz sensitivity.}, number = {6}, journal = {Physical Review A}, author = {Jasperse, M. and Kewming, M. J. and Fischer, S. N. and Pakkiam, P. and Anderson, R. P. and Turner, L. D.}, month = dec, year = {2017}, eprint = {1705.10965}, pages = {063402} }
- Precise wave-function engineering with magnetic resonance,
P. B. Wigley, L. M. Starkey, S. S. Szigeti, M. Jasperse, J. J. Hope, L. D. Turner, and R. P. Anderson.
Physical Review A 96, 13612 (2017).
[arXiv] [DOI] [Bibtex] [Abstract]
Controlling quantum fluids at their fundamental length scale will yield superlative quantum simulators, precision sensors, and spintronic devices. This scale is typically below the optical diffraction limit, precluding precise wave-function engineering using optical potentials alone. We present a protocol to rapidly control the phase and density of a quantum fluid down to the healing length scale using strong time-dependent coupling between internal states of the fluid in a magnetic field gradient. We demonstrate this protocol by simulating the creation of a single stationary soliton and double soliton states in a Bose-Einstein condensate with control over the individual soliton positions and trajectories, using experimentally feasible parameters. Such states are yet to be realized experimentally, and are a path towards engineering soliton gases and exotic topological excitations.
@article{wigley_precise_2017, title = {Precise wave-function engineering with magnetic resonance}, volume = {96}, url = {https://link.aps.org/doi/10.1103/PhysRevA.96.013612}, doi = {10.1103/PhysRevA.96.013612}, abstract = {Controlling quantum fluids at their fundamental length scale will yield superlative quantum simulators, precision sensors, and spintronic devices. This scale is typically below the optical diffraction limit, precluding precise wave-function engineering using optical potentials alone. We present a protocol to rapidly control the phase and density of a quantum fluid down to the healing length scale using strong time-dependent coupling between internal states of the fluid in a magnetic field gradient. We demonstrate this protocol by simulating the creation of a single stationary soliton and double soliton states in a Bose-Einstein condensate with control over the individual soliton positions and trajectories, using experimentally feasible parameters. Such states are yet to be realized experimentally, and are a path towards engineering soliton gases and exotic topological excitations.}, number = {1}, journal = {Physical Review A}, author = {Wigley, P. B. and Starkey, L. M. and Szigeti, S. S. and Jasperse, M. and Hope, J. J. and Turner, L. D. and Anderson, R. P.}, month = jul, year = {2017}, eprint = {1412.6854}, pages = {013612} }
- Suspending test masses in terrestrial millihertz gravitational-wave detectors: a case study with a magnetic assisted torsion pendulum,
E. Thrane, R. P. Anderson, Y. Levin, and L. D. Turner.
Classical and Quantum Gravity 34, 105002 (2017).
[arXiv] [DOI] [Bibtex] [Abstract]
Current terrestrial gravitational-wave detectors operate at frequencies above 10 Hz. There is strong astrophysical motivation to construct low-frequency gravitational-wave detectors capable of observing 10 mHz–10 Hz signals. While space-based detectors provide one means of achieving this end, one may also consider terretrial detectors. However, there are numerous technological challenges. In particular, it is difficult to isolate test masses so that they are both seismically isolated and freely falling under the influence of gravity at millihertz frequencies. We investigate the challenges of low-frequency suspension in a hypothetical terrestrial detector. As a case study, we consider a magnetically assisted gravitational-wave pendulum intorsion (MAGPI) suspension design. We construct a noise budget to estimate some of the required specifications. In doing so, we identify what are likely to be a number of generic limiting noise sources for terrestrial millihertz gravitational-wave suspension systems (as well as some peculiar to the MAGPI design). We highlight significant experimental challenges in order to argue that the development of millihertz suspensions will be a daunting task. Any system that relies on magnets faces even greater challenges. Entirely mechanical designs such as Zöllner pendulums may provide the best path forward.
@article{thrane_suspending_2017, title = {Suspending test masses in terrestrial millihertz gravitational-wave detectors: a case study with a magnetic assisted torsion pendulum}, volume = {34}, issn = {0264-9381}, shorttitle = {Suspending test masses in terrestrial millihertz gravitational-wave detectors}, url = {http://stacks.iop.org/0264-9381/34/i=10/a=105002}, doi = {10.1088/1361-6382/aa6968}, abstract = {Current terrestrial gravitational-wave detectors operate at frequencies above 10 Hz. There is strong astrophysical motivation to construct low-frequency gravitational-wave detectors capable of observing 10 mHz–10 Hz signals. While space-based detectors provide one means of achieving this end, one may also consider terretrial detectors. However, there are numerous technological challenges. In particular, it is difficult to isolate test masses so that they are both seismically isolated and freely falling under the influence of gravity at millihertz frequencies. We investigate the challenges of low-frequency suspension in a hypothetical terrestrial detector. As a case study, we consider a magnetically assisted gravitational-wave pendulum intorsion (MAGPI) suspension design. We construct a noise budget to estimate some of the required specifications. In doing so, we identify what are likely to be a number of generic limiting noise sources for terrestrial millihertz gravitational-wave suspension systems (as well as some peculiar to the MAGPI design). We highlight significant experimental challenges in order to argue that the development of millihertz suspensions will be a daunting task. Any system that relies on magnets faces even greater challenges. Entirely mechanical designs such as Zöllner pendulums may provide the best path forward.}, number = {10}, urldate = {2017-06-01TZ}, journal = {Classical and Quantum Gravity}, author = {Thrane, Eric and Anderson, Russell P. and Levin, Yuri and Turner, L. D.}, year = {2017}, eprint = {1512.03137}, pages = {105002} }
2016
- Measurement and extinction of vector light shifts using interferometry of spinor condensates,
A. A. Wood, L. D. Turner, and R. P. Anderson.
Physical Review A 94, 52503 (2016).
[arXiv] [DOI] [Bibtex]@article{wood_measurement_2016, title = {Measurement and extinction of vector light shifts using interferometry of spinor condensates}, volume = {94}, url = {http://link.aps.org/doi/10.1103/PhysRevA.94.052503}, doi = {10.1103/PhysRevA.94.052503}, number = {5}, journal = {Physical Review A}, author = {Wood, A. A. and Turner, L. D. and Anderson, R. P.}, month = nov, year = {2016}, eprint = {1607.06898}, pages = {052503} }
- Precise engineering of the Bose–Einstein condensate wavefunction using magnetic resonance control,
L. M. Starkey, PhD Thesis.
[DOI] [Bibtex] [Abstract]
This thesis develops a new way to sculpt the coldest matter in the universe, a Bose-Einstein condensate, using methods inspired by the medical diagnostic technique of magnetic resonance imaging. This superfluid matter, first predicted by Bose and Einstein in 1925, manifests quantum behaviour at the macroscopic scale. We demonstrate how to shape the finest structures into this matter with unprecedented control, with the future goal of observing structures which have never been created before in quantum fluids, and causing this matter to mimic other physical phenomena.
@phdthesis{starkey_precise_2016, type = {{PhD} thesis}, title = {Precise engineering of the {Bose--Einstein} condensate wavefunction using magnetic resonance control}, url = {http://dx.doi.org/1959.1/1278937}, abstract = {This thesis develops a new way to sculpt the coldest matter in the universe, a Bose-Einstein condensate, using methods inspired by the medical diagnostic technique of magnetic resonance imaging. This superfluid matter, first predicted by Bose and Einstein in 1925, manifests quantum behaviour at the macroscopic scale. We demonstrate how to shape the finest structures into this matter with unprecedented control, with the future goal of observing structures which have never been created before in quantum fluids, and causing this matter to mimic other physical phenomena.}, school = {Monash University}, author = {Starkey, L. M.}, month = jul, year = {2016}, doi = {1959.1/1278937} }
- Sub-kilohertz laser linewidth narrowing using polarization spectroscopy,
J. S. Torrance, B. M. Sparkes, L. D. Turner, and R. E. Scholten.
Optics Express 24, 11396-11406 (2016).
[DOI] [Bibtex] [Abstract]
We identify several beneficial characteristics of polarization spectroscopy as an absolute atomic reference for frequency stabilization of lasers, and demonstrate sub-kilohertz laser spectral linewidth narrowing using polarization spectroscopy with high-bandwidth feedback. Polarization spectroscopy provides a highly dispersive velocity-selective absolute atomic reference based on frequency-dependent birefringence in an optically pumped atomic gas. The pumping process leads to dominance of the primary closed transition, suppressing closely-spaced subsidiary resonances which reduce the effective capture range for conventional atomic references. The locking signal is based on subtraction of two orthogonal polarization signals, reducing the effect of laser intensity noise to the shot noise limit. We measure noise-limited servo bandwidth comparable to that of a high-finesse optical cavity without the frequency limit or complexity imposed by optical modulation normally associated with high bandwidth laser frequency stabilization. We demonstrate narrowing to 600&\#x000B1;100 Hz laser linewidth using the beatnote between two similarly locked external cavity diode lasers.
@article{torrance_sub-kilohertz_2016, title = {Sub-kilohertz laser linewidth narrowing using polarization spectroscopy}, volume = {24}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-24-11-11396}, doi = {10.1364/OE.24.011396}, abstract = {We identify several beneficial characteristics of polarization spectroscopy as an absolute atomic reference for frequency stabilization of lasers, and demonstrate sub-kilohertz laser spectral linewidth narrowing using polarization spectroscopy with high-bandwidth feedback. Polarization spectroscopy provides a highly dispersive velocity-selective absolute atomic reference based on frequency-dependent birefringence in an optically pumped atomic gas. The pumping process leads to dominance of the primary closed transition, suppressing closely-spaced subsidiary resonances which reduce the effective capture range for conventional atomic references. The locking signal is based on subtraction of two orthogonal polarization signals, reducing the effect of laser intensity noise to the shot noise limit. We measure noise-limited servo bandwidth comparable to that of a high-finesse optical cavity without the frequency limit or complexity imposed by optical modulation normally associated with high bandwidth laser frequency stabilization. We demonstrate narrowing to 600\&\#x000B1;100 Hz laser linewidth using the beatnote between two similarly locked external cavity diode lasers.}, number = {11}, journal = {Optics Express}, author = {Torrance, Joshua S. and Sparkes, Ben M. and Turner, Lincoln D. and Scholten, Robert E.}, month = may, year = {2016}, doi = {10.1364/OE.24.011396}, keywords = {Laser stabilization, Spectroscopy, atomic}, pages = {11396--11406} }
2015
- Faraday Magnetic Resonance Imaging of Bose–Einstein Condensates,
M. Jasperse, PhD Thesis.
[DOI] [Bibtex] [Abstract]
This thesis demonstrates the first ever magnetic resonance image, or MRI, of the coldest matter in the Universe. This superfluid – predicted by Einstein in 1925 – exhibits the curious hallmarks of quantum physics that occur inside atoms, but on a much larger length scale. Nevertheless, traditional imaging methods using lenses and cameras fail to see the finest structure of this matter without destroying it. This thesis closes the circle of reciprocity between fundamental science and medicine, applying a diagnostic imaging technique borne out of nuclear physics 40 years ago to cutting-edge atomic physics.
@phdthesis{jasperse_faraday_2015, type = {{PhD} thesis}, title = {Faraday Magnetic Resonance Imaging of {Bose--Einstein} Condensates}, url = {http://dx.doi.org/1959.1/1231988}, abstract = {This thesis demonstrates the first ever magnetic resonance image, or MRI, of the coldest matter in the Universe. This superfluid – predicted by Einstein in 1925 – exhibits the curious hallmarks of quantum physics that occur inside atoms, but on a much larger length scale. Nevertheless, traditional imaging methods using lenses and cameras fail to see the finest structure of this matter without destroying it. This thesis closes the circle of reciprocity between fundamental science and medicine, applying a diagnostic imaging technique borne out of nuclear physics 40 years ago to cutting-edge atomic physics.}, school = {Monash University}, author = {Jasperse, M.}, month = dec, year = {2015}, doi = {1959.1/1231988} }
- Spinor Bose–Einstein condensates in magnetic field gradients,
A. A. Wood, PhD Thesis.
[DOI] [Bibtex] [Abstract]
This thesis develops a new kind of microscope for magnetic fields, using the coldest matter in the Universe. The medium is an exotic phase of matter – first predicted by Einstein in 1925 – exquisitely cold, and exquisitely sensitive to magnetic fields. The magnetic microscope can ‘see’ both real magnetic fields and fictitious ones produced by lasers, and does not require calibration or shielding from ambient fields. It may be applied to imaging cellular function, detecting vehicles and unexploded ordinance, and the fundamental physics of ultracold atoms in its own right.
@phdthesis{wood_spinor_2015, type = {{PhD} thesis}, title = {Spinor {Bose--Einstein} condensates in magnetic field gradients}, url = {http://dx.doi.org/1959.1/1228163}, abstract = {This thesis develops a new kind of microscope for magnetic fields, using the coldest matter in the Universe. The medium is an exotic phase of matter - first predicted by Einstein in 1925 - exquisitely cold, and exquisitely sensitive to magnetic fields. The magnetic microscope can 'see' both real magnetic fields and fictitious ones produced by lasers, and does not require calibration or shielding from ambient fields. It may be applied to imaging cellular function, detecting vehicles and unexploded ordinance, and the fundamental physics of ultracold atoms in its own right.}, school = {Monash University}, author = {Wood, A. A.}, month = nov, year = {2015}, doi = {1959.1/1228163} }
- Magnetic tensor gradiometry using Ramsey interferometry of spinor condensates,
A. A. Wood, L. M. Bennie, A. Duong, M. Jasperse, L. D. Turner, and R. P. Anderson.
Physical Review A 92, 53604 (2015).
[arXiv] [DOI] [Bibtex] [Abstract]
We have realized a magnetic tensor gradiometer by interferometrically measuring the relative phase between two spatially separated Bose-Einstein condensates (BECs). We perform simultaneous Ramsey interferometry of the proximate Rb87 spin-1 condensates in free fall and infer their relative Larmor phase, and thus the differential magnetic-field strength, with a common-mode phase noise suppression exceeding 50dB. By appropriately biasing the magnetic field and separating the BECs along orthogonal directions, we measure in vacuo the magnetic-field-gradient tensor of ambient and applied magnetic fields with a nominal precision of 0.30nTmm−1 and a sensor volume of 2×10−5mm3. We predict a spin-projection noise-limited magnetic energy resolution of order ∼10ℏ for typical Zeeman coherence times of trapped condensates with this scheme, even with the low measurement duty cycle of current BEC experiments.
@article{wood_magnetic_2015, title = {Magnetic tensor gradiometry using Ramsey interferometry of spinor condensates}, volume = {92}, url = {http://link.aps.org/doi/10.1103/PhysRevA.92.053604}, doi = {10.1103/PhysRevA.92.053604}, abstract = {We have realized a magnetic tensor gradiometer by interferometrically measuring the relative phase between two spatially separated Bose-Einstein condensates (BECs). We perform simultaneous Ramsey interferometry of the proximate Rb87 spin-1 condensates in free fall and infer their relative Larmor phase, and thus the differential magnetic-field strength, with a common-mode phase noise suppression exceeding 50dB. By appropriately biasing the magnetic field and separating the BECs along orthogonal directions, we measure in vacuo the magnetic-field-gradient tensor of ambient and applied magnetic fields with a nominal precision of 0.30nTmm−1 and a sensor volume of 2×10−5mm3. We predict a spin-projection noise-limited magnetic energy resolution of order ∼10ℏ for typical Zeeman coherence times of trapped condensates with this scheme, even with the low measurement duty cycle of current BEC experiments.}, number = {5}, urldate = {2016-01-04TZ}, journal = {Physical Review A}, author = {Wood, A. A. and Bennie, L. M. and Duong, A. and Jasperse, M. and Turner, L. D. and Anderson, R. P.}, month = nov, year = {2015}, eprint = {1408.0944}, pages = {053604} }
- A Monte Carlo wavefunction method for semiclassical simulations of spin-position entanglement,
C. J. Billington, C. J. Watkins, R. P. Anderson, and L. D. Turner.
[arXiv] [Bibtex] [Abstract]
We present a Monte Carlo wavefunction method for semiclassically modeling spin-\${\textbackslash}frac12\$ systems in a magnetic field gradient in one dimension. Our model resolves the conflict of determining what classical force an atom should be subjected to when it is in an arbitrary superposition of internal states. Spatial degrees of freedom are considered to be an environment, entanglement with which decoheres the internal states. Atoms follow classical trajectories through space, punctuated by probabilistic jumps between spin states. We modify the conventional Monte Carlo wavefunction method to jump between states when population transfer occurs, rather than when population is later discarded via exponential decay. This results in a spinor wavefunction that is continuous in time, and allows us to model the classical particle trajectories (evolution of the environment variables) more accurately. The model is not computationally demanding and it agrees well with simulations of the full spatial wavefunction of an atom.
@article{billington_monte_2015, title = {{A} Monte Carlo wavefunction method for semiclassical simulations of spin-position entanglement}, url = {http://arxiv.org/abs/1502.06674}, abstract = {We present a Monte Carlo wavefunction method for semiclassically modeling spin-\${\textbackslash}frac12\$ systems in a magnetic field gradient in one dimension. Our model resolves the conflict of determining what classical force an atom should be subjected to when it is in an arbitrary superposition of internal states. Spatial degrees of freedom are considered to be an environment, entanglement with which decoheres the internal states. Atoms follow classical trajectories through space, punctuated by probabilistic jumps between spin states. We modify the conventional Monte Carlo wavefunction method to jump between states when population transfer occurs, rather than when population is later discarded via exponential decay. This results in a spinor wavefunction that is continuous in time, and allows us to model the classical particle trajectories (evolution of the environment variables) more accurately. The model is not computationally demanding and it agrees well with simulations of the full spatial wavefunction of an atom.}, urldate = {2016-01-04TZ}, journal = {arXiv:1502.06674}, author = {Billington, C. J. and Watkins, C. J. and Anderson, R. P. and Turner, L. D.}, month = feb, year = {2015}, eprint = {1502.06674}, keywords = {Physics - Atomic Physics, Quantum Physics} }
2014
- Self-induced spatial dynamics to enhance spin squeezing via one-axis twisting in a two-component Bose–Einstein condensate,
S. A. Haine, J. Lau, R. P. Anderson, and M. T. Johnsson.
Physical Review A 90, 23613 (2014).
[arXiv] [DOI] [Bibtex] [Abstract]
We theoretically investigate a scheme to enhance relative number squeezing and spin squeezing in a two-component Bose-Einstein condensate (BEC) by utilizing the inherent mean-field dynamics of the condensate. Due to the asymmetry in the scattering lengths, the two components exhibit large density oscillations where they spatially separate and recombine. The effective nonlinearity responsible for the squeezing is increased by up to 3 orders of magnitude when the two components spatially separate. We perform a multimode simulation of the system using the truncated Wigner method and show that this method can be used to create significant squeezing in systems where the effective nonlinearity would ordinarily be too small to produce any significant squeezing in sensible time frames, and we show that strong spatial dynamics resulting from large particle numbers aren’t necessarily detrimental to generating squeezing. We develop a simplified semianalytic model that gives good agreement with our multimode simulation and will be useful for predicting squeezing in a range of different systems.
@article{haine_self-induced_2014, title = {Self-induced spatial dynamics to enhance spin squeezing via one-axis twisting in a two-component {Bose--Einstein} condensate}, volume = {90}, url = {http://link.aps.org/doi/10.1103/PhysRevA.90.023613}, doi = {10.1103/PhysRevA.90.023613}, abstract = {We theoretically investigate a scheme to enhance relative number squeezing and spin squeezing in a two-component Bose-Einstein condensate (BEC) by utilizing the inherent mean-field dynamics of the condensate. Due to the asymmetry in the scattering lengths, the two components exhibit large density oscillations where they spatially separate and recombine. The effective nonlinearity responsible for the squeezing is increased by up to 3 orders of magnitude when the two components spatially separate. We perform a multimode simulation of the system using the truncated Wigner method and show that this method can be used to create significant squeezing in systems where the effective nonlinearity would ordinarily be too small to produce any significant squeezing in sensible time frames, and we show that strong spatial dynamics resulting from large particle numbers aren't necessarily detrimental to generating squeezing. We develop a simplified semianalytic model that gives good agreement with our multimode simulation and will be useful for predicting squeezing in a range of different systems.}, number = {2}, urldate = {2016-01-04TZ}, journal = {Physical Review A}, author = {Haine, S. A. and Lau, J. and Anderson, R. P. and Johnsson, M. T.}, month = aug, year = {2014}, eprint = {1402.0307}, pages = {023613} }
2013
- A scripted control system for autonomous hardware-timed experiments,
P. T. Starkey, C. J. Billington, S. P. Johnstone, M. Jasperse, K. Helmerson, L. D. Turner, and R. P. Anderson.
Review of Scientific Instruments 84, 85111 (2013).
[arXiv] [DOI] [Bibtex] [Abstract]
We present the labscript suite, an open-source experiment control system for automating shot-based experiments and their analysis. Experiments are composed as Python code, which is used to produce low-level hardware instructions. They are queued up and executed on the hardware in real time, synchronized by a pseudoclock. Experiment parameters are manipulated graphically, and analysis routines are run as new data are acquired. With this system, we can easily automate exploration of parameter spaces, including closed-loop optimization.
@article{starkey_scripted_2013, title = {{A} scripted control system for autonomous hardware-timed experiments}, volume = {84}, issn = {0034-6748, 1089-7623}, url = {http://scitation.aip.org/content/aip/journal/rsi/84/8/10.1063/1.4817213}, doi = {10.1063/1.4817213}, abstract = {We present the labscript suite, an open-source experiment control system for automating shot-based experiments and their analysis. Experiments are composed as Python code, which is used to produce low-level hardware instructions. They are queued up and executed on the hardware in real time, synchronized by a pseudoclock. Experiment parameters are manipulated graphically, and analysis routines are run as new data are acquired. With this system, we can easily automate exploration of parameter spaces, including closed-loop optimization.}, number = {8}, urldate = {2014-04-25TZ}, journal = {Review of Scientific Instruments}, author = {Starkey, P. T. and Billington, C. J. and Johnstone, S. P. and Jasperse, M. and Helmerson, K. and Turner, L. D. and Anderson, R. P.}, month = aug, year = {2013}, eprint = {1303.0080}, pages = {085111} }
- PHI: A powerful new program for the analysis of anisotropic monomeric and exchange-coupled polynuclear d- and f-block complexes,
N. F. Chilton, R. P. Anderson, L. D. Turner, A. Soncini, and K. S. Murray.
Journal of Computational Chemistry 34, 1164-1175 (2013).
[DOI] [Bibtex] [Abstract]
A new program, PHI, with the ability to calculate the magnetic properties of large spin systems and complex orbitally degenerate systems, such as clusters of d-block and f-block ions, is presented. The program can intuitively fit experimental data from multiple sources, such as magnetic and spectroscopic data, simultaneously. PHI is extensively parallelized and can operate under the symmetric multiprocessing, single process multiple data, or GPU paradigms using a threaded, MPI or GPU model, respectively. For a given problem PHI is been shown to be almost 12 times faster than the well-known program MAGPACK, limited only by available hardware. © 2013 Wiley Periodicals, Inc.
@article{chilton_phi:_2013, title = {{PHI:} {A} powerful new program for the analysis of anisotropic monomeric and exchange-coupled polynuclear d- and f-block complexes}, volume = {34}, copyright = {Copyright © 2013 Wiley Periodicals, Inc.}, issn = {1096-987X}, shorttitle = {{PHI}}, url = {http://onlinelibrary.wiley.com/doi/10.1002/jcc.23234/abstract}, doi = {10.1002/jcc.23234}, abstract = {A new program, PHI, with the ability to calculate the magnetic properties of large spin systems and complex orbitally degenerate systems, such as clusters of d-block and f-block ions, is presented. The program can intuitively fit experimental data from multiple sources, such as magnetic and spectroscopic data, simultaneously. PHI is extensively parallelized and can operate under the symmetric multiprocessing, single process multiple data, or GPU paradigms using a threaded, MPI or GPU model, respectively. For a given problem PHI is been shown to be almost 12 times faster than the well-known program MAGPACK, limited only by available hardware. © 2013 Wiley Periodicals, Inc.}, number = {13}, urldate = {2014-04-25TZ}, journal = {Journal of Computational Chemistry}, author = {Chilton, Nicholas F. and Anderson, Russell P. and Turner, Lincoln D. and Soncini, Alessandro and Murray, Keith S.}, month = may, year = {2013}, pages = {1164--1175} }
- A versatile high resolution objective for imaging quantum gases,
L. M. Bennie, P. T. Starkey, M. Jasperse, C. J. Billington, R. P. Anderson, and L. D. Turner.
Optics Express 21, 9011-9016 (2013).
[arXiv] [DOI] [Bibtex] [Abstract]
We present a high resolution objective lens made entirely from catalog singlets that has a numerical aperture of 0.36. It corrects for aberrations introduced by a glass window and has a long working distance of 35 mm, making it suitable for imaging objects within a vacuum system. This offers simple high resolution imaging for many in the quantum gas community. The objective achieves a resolution of 1.3 μm at the design wavelength of 780 nm, and a diffraction-limited field of view of 360 μm when imaging through a 5 mm thick window. Images of a resolution target and a pinhole show quantitative agreement with the simulated lens performance. The objective is suitable for diffraction-limited monochromatic imaging on the D2 line of all the alkalis by changing only the aperture diameter, retaining numerical apertures above 0.32. The design corrects for window thicknesses of up to 15 mm if the singlet spacings are modified.
@article{bennie_versatile_2013, title = {{A} versatile high resolution objective for imaging quantum gases}, volume = {21}, url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-21-7-9011}, doi = {10.1364/OE.21.009011}, abstract = {We present a high resolution objective lens made entirely from catalog singlets that has a numerical aperture of 0.36. It corrects for aberrations introduced by a glass window and has a long working distance of 35 mm, making it suitable for imaging objects within a vacuum system. This offers simple high resolution imaging for many in the quantum gas community. The objective achieves a resolution of 1.3 μm at the design wavelength of 780 nm, and a diffraction-limited field of view of 360 μm when imaging through a 5 mm thick window. Images of a resolution target and a pinhole show quantitative agreement with the simulated lens performance. The objective is suitable for diffraction-limited monochromatic imaging on the D2 line of all the alkalis by changing only the aperture diameter, retaining numerical apertures above 0.32. The design corrects for window thicknesses of up to 15 mm if the singlet spacings are modified.}, number = {7}, urldate = {2014-04-25TZ}, journal = {Optics Express}, author = {Bennie, L. M. and Starkey, P. T. and Jasperse, M. and Billington, C. J. and Anderson, R. P. and Turner, L. D.}, month = apr, year = {2013}, eprint = {1302.4166}, pages = {9011--9016} }
- Wideband laser locking to an atomic reference with modulation transfer spectroscopy,
V. Negnevitsky and L. D. Turner.
Optics Express 21, 3103 (2013).
[arXiv] [DOI] [Bibtex] [Abstract]
We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.
@article{negnevitsky_wideband_2013, title = {Wideband laser locking to an atomic reference with modulation transfer spectroscopy}, volume = {21}, issn = {1094-4087}, url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-21-3-3103}, doi = {10.1364/OE.21.003103}, abstract = {We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.}, number = {3}, urldate = {2016-01-04TZ}, journal = {Optics Express}, author = {Negnevitsky, V. and Turner, L. D.}, month = feb, year = {2013}, eprint = {1204.5240}, pages = {3103} }
- Precision atomic gravimeter based on Bragg diffraction,
P. A. Altin, M. T. Johnsson, V. Negnevitsky, G. R. Dennis, R. P. Anderson, J. E. Debs, S. S. Szigeti, K. S. Hardman, S. Bennetts, G. D. McDonald, L. D. Turner, J. D. Close, and N. P. Robins.
New Journal of Physics 15, 23009 (2013).
[arXiv] [DOI] [Bibtex] [Abstract]
We present a precision gravimeter based on coherent Bragg diffraction of freely falling cold atoms. Traditionally, atomic gravimeters have used stimulated Raman transitions to separate clouds in momentum space by driving transitions between two internal atomic states. Bragg interferometers utilize only a single internal state, and can therefore be less susceptible to environmental perturbations. Here we show that atoms extracted from a magneto-optical trap using an accelerating optical lattice are a suitable source for a Bragg atom interferometer, allowing efficient beamsplitting and subsequent separation of momentum states for detection. Despite the inherently multi-state nature of atom diffraction, we are able to build a Mach–Zehnder interferometer using Bragg scattering which achieves a sensitivity to the gravitational acceleration of Δg/g = 2.7 × 10−9 with an integration time of 1000 s. The device can also be converted to a gravity gradiometer by a simple modification of the light pulse sequence.
@article{altin_precision_2013, title = {Precision atomic gravimeter based on {Bragg} diffraction}, volume = {15}, issn = {1367-2630}, url = {http://iopscience.iop.org/1367-2630/15/2/023009}, doi = {10.1088/1367-2630/15/2/023009}, abstract = {We present a precision gravimeter based on coherent Bragg diffraction of freely falling cold atoms. Traditionally, atomic gravimeters have used stimulated Raman transitions to separate clouds in momentum space by driving transitions between two internal atomic states. Bragg interferometers utilize only a single internal state, and can therefore be less susceptible to environmental perturbations. Here we show that atoms extracted from a magneto-optical trap using an accelerating optical lattice are a suitable source for a Bragg atom interferometer, allowing efficient beamsplitting and subsequent separation of momentum states for detection. Despite the inherently multi-state nature of atom diffraction, we are able to build a Mach–Zehnder interferometer using Bragg scattering which achieves a sensitivity to the gravitational acceleration of Δg/g = 2.7 × 10−9 with an integration time of 1000 s. The device can also be converted to a gravity gradiometer by a simple modification of the light pulse sequence.}, number = {2}, urldate = {2014-04-25TZ}, journal = {New Journal of Physics}, author = {Altin, P. A. and Johnsson, M. T. and Negnevitsky, V. and Dennis, G. R. and Anderson, R. P. and Debs, J. E. and Szigeti, S. S. and Hardman, K. S. and Bennetts, S. and McDonald, G. D. and Turner, L. D. and Close, J. D. and Robins, N. P.}, month = feb, year = {2013}, eprint = {1207.1595}, pages = {023009} }
2012
- Partial-transfer absorption imaging: A versatile technique for optimal imaging of ultracold gases,
A. Ramanathan, S. R. Muniz, K. C. Wright, R. P. Anderson, W. D. Phillips, K. Helmerson, and G. K. Campbell.
Review of Scientific Instruments 83, 83119 (2012).
[arXiv] [DOI] [Bibtex] [Abstract]
Partial-transfer absorption imaging is a tool that enables optimal imaging of atomic clouds for a wide range of optical depths. In contrast to standard absorption imaging, the technique can be minimally destructive and can be used to obtain multiple successive images of the same sample. The technique involves transferring a small fraction of the sample from an initial internal atomic state to an auxiliary state and subsequently imaging that fraction absorptively on a cycling transition. The atoms remaining in the initial state are essentially unaffected. We demonstrate the technique, discuss its applicability, and compare its performance as a minimally destructive technique to that of phase-contrast imaging.
@article{ramanathan_partial-transfer_2012, title = {Partial-transfer absorption imaging: {A} versatile technique for optimal imaging of ultracold gases}, volume = {83}, issn = {0034-6748, 1089-7623}, shorttitle = {Partial-transfer absorption imaging}, url = {http://scitation.aip.org/content/aip/journal/rsi/83/8/10.1063/1.4747163}, doi = {10.1063/1.4747163}, abstract = {Partial-transfer absorption imaging is a tool that enables optimal imaging of atomic clouds for a wide range of optical depths. In contrast to standard absorption imaging, the technique can be minimally destructive and can be used to obtain multiple successive images of the same sample. The technique involves transferring a small fraction of the sample from an initial internal atomic state to an auxiliary state and subsequently imaging that fraction absorptively on a cycling transition. The atoms remaining in the initial state are essentially unaffected. We demonstrate the technique, discuss its applicability, and compare its performance as a minimally destructive technique to that of phase-contrast imaging.}, number = {8}, urldate = {2014-04-25TZ}, journal = {Review of Scientific Instruments}, author = {Ramanathan, Anand and Muniz, Sérgio R. and Wright, Kevin C. and Anderson, Russell P. and Phillips, William D. and Helmerson, Kristian and Campbell, Gretchen K.}, month = aug, year = {2012}, eprint = {1206.7048}, pages = {083119} }
2011
- Cold-atom gravimetry with a Bose–Einstein condensate,
J. E. Debs, P. A. Altin, T. H. Barter, D. Döring, G. R. Dennis, G. McDonald, R. P. Anderson, J. D. Close, and N. P. Robins.
Physical Review A 84, 33610 (2011).
[arXiv] [DOI] [Bibtex] [Abstract]
We present a cold-atom gravimeter operating with a sample of Bose-condensed 87Rb atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of (83±6)\% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources and observe a reduced visibility of (58±4)\% for the thermal source. We suspect the loss in visibility is caused partly by wave-front aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and we present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely falling, coherent atomic sources.
@article{debs_cold-atom_2011, title = {Cold-atom gravimetry with a {Bose--Einstein} condensate}, volume = {84}, url = {http://link.aps.org/doi/10.1103/PhysRevA.84.033610}, doi = {10.1103/PhysRevA.84.033610}, abstract = {We present a cold-atom gravimeter operating with a sample of Bose-condensed 87Rb atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of (83±6)\% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources and observe a reduced visibility of (58±4)\% for the thermal source. We suspect the loss in visibility is caused partly by wave-front aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and we present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely falling, coherent atomic sources.}, number = {3}, urldate = {2012-02-06TZ}, journal = {Physical Review A}, author = {Debs, J. E. and Altin, P. A. and Barter, T. H. and Döring, D. and Dennis, G. R. and McDonald, G. and Anderson, R. P. and Close, J. D. and Robins, N. P.}, month = sep, year = {2011}, eprint = {1011.5804}, pages = {033610} }
- Long-lived periodic revivals of coherence in an interacting Bose–Einstein condensate,
M. Egorov, R. P. Anderson, V. Ivannikov, B. Opanchuk, P. Drummond, B. V. Hall, and A. I. Sidorov.
Physical Review A 84, 21605 (2011).
[arXiv] [DOI] [Bibtex] [Abstract]
We observe the coherence of an interacting two-component Bose-Einstein condensate (BEC) surviving for seconds in a trapped Ramsey interferometer. Mean-field-driven collective oscillations of two components lead to periodic dephasing and rephasing of condensate wave functions with a slow decay of the interference fringe visibility. We apply spin echo synchronous with the self-rephasing of the condensate to reduce the influence of state-dependent atom losses, significantly enhancing the visibility up to 0.75 at the evolution time of 1.5 s. Mean-field theory consistently predicts higher visibility than experimentally observed values. We quantify the effects of classical and quantum noise and infer a coherence time of 2.8 s for a trapped condensate of 5.5×104 interacting atoms.
@article{egorov_long-lived_2011, title = {Long-lived periodic revivals of coherence in an interacting {Bose--Einstein} condensate}, volume = {84}, url = {http://link.aps.org/doi/10.1103/PhysRevA.84.021605}, doi = {10.1103/PhysRevA.84.021605}, abstract = {We observe the coherence of an interacting two-component Bose-Einstein condensate (BEC) surviving for seconds in a trapped Ramsey interferometer. Mean-field-driven collective oscillations of two components lead to periodic dephasing and rephasing of condensate wave functions with a slow decay of the interference fringe visibility. We apply spin echo synchronous with the self-rephasing of the condensate to reduce the influence of state-dependent atom losses, significantly enhancing the visibility up to 0.75 at the evolution time of 1.5 s. Mean-field theory consistently predicts higher visibility than experimentally observed values. We quantify the effects of classical and quantum noise and infer a coherence time of 2.8 s for a trapped condensate of 5.5×104 interacting atoms.}, number = {2}, urldate = {2012-02-06TZ}, journal = {Physical Review A}, author = {Egorov, M. and Anderson, R. P. and Ivannikov, V. and Opanchuk, B. and Drummond, P. and Hall, B. V. and Sidorov, A. I.}, month = aug, year = {2011}, eprint = {1012.3813}, pages = {021605} }
- Optically trapped atom interferometry using the clock transition of large $^{87}$Rb Bose–Einstein condensates,
P. A. Altin, G. McDonald, D. Döring, J. E. Debs, T. H. Barter, J. D. Close, N. P. Robins, S. A. Haine, T. M. Hanna, and R. P. Anderson.
New Journal of Physics 13, 65020 (2011).
[arXiv] [DOI] [Bibtex]@article{altin_optically_2011, title = {Optically trapped atom interferometry using the clock transition of large {$^{87}$Rb} {Bose}–{Einstein} condensates}, volume = {13}, issn = {1367-2630}, url = {http://iopscience.iop.org/1367-2630/13/6/065020}, doi = {10.1088/1367-2630/13/6/065020}, number = {6}, urldate = {2012-02-06TZ}, journal = {New Journal of Physics}, author = {Altin, P A and McDonald, G and Döring, D and Debs, J E and Barter, T H and Close, J D and Robins, N P and Haine, S A and Hanna, T M and Anderson, R P}, month = jun, year = {2011}, eprint = {1011.4713}, pages = {065020} }
- Relative intensity squeezing by four-wave mixing with loss: an analytic model and experimental diagnostic,
M. Jasperse, L. D. Turner, and R. E. Scholten.
Optics Express 19, 3765 (2011).
[arXiv] [DOI] [Bibtex] [Abstract]
Four-wave mixing near resonance in an atomic vapor can produce relative intensity squeezed light suitable for precision measurements beyond the shot-noise limit. We develop an analytic distributed gain/loss model to describe the competition of mixing and absorption through the non-linear medium. Using a novel matrix calculus, we present closed-form expressions for the degree of relative intensity squeezing produced by this system. We use these theoretical results to analyze experimentally measured squeezing from a 85Rb vapor and demonstrate the analytic model’s utility as an experimental diagnostic.
@article{jasperse_relative_2011, title = {Relative intensity squeezing by four-wave mixing with loss: an analytic model and experimental diagnostic}, volume = {19}, issn = {1094-4087}, shorttitle = {Relative intensity squeezing by four-wave mixing with loss}, url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-19-4-3765}, doi = {10.1364/OE.19.003765}, abstract = {Four-wave mixing near resonance in an atomic vapor can produce relative intensity squeezed light suitable for precision measurements beyond the shot-noise limit. We develop an analytic distributed gain/loss model to describe the competition of mixing and absorption through the non-linear medium. Using a novel matrix calculus, we present closed-form expressions for the degree of relative intensity squeezing produced by this system. We use these theoretical results to analyze experimentally measured squeezing from a 85Rb vapor and demonstrate the analytic model’s utility as an experimental diagnostic.}, number = {4}, urldate = {2016-01-04TZ}, journal = {Optics Express}, author = {Jasperse, M. and Turner, L. D. and Scholten, R. E.}, month = feb, year = {2011}, eprint = {1012.3482}, pages = {3765} }
2010
- A slow atom source using a collimated effusive oven and a single-layer variable pitch coil Zeeman slower,
S. C. Bell, M. Junker, M. Jasperse, L. D. Turner, Y. -J. Lin, I. B. Spielman, and R. E. Scholten.
Review of Scientific Instruments 81, 13105 (2010).
[DOI] [Bibtex] [Abstract]
We describe a simple slow atom source for loading a rubidiummagneto-optical trap. The source includes an effusive oven with a long heated collimation tube. Almost all components are standard vacuum parts. The heating elements and thermocouples are external to the vacuum, protecting them from the hostile hot alkali environment and allowing repair without breaking vacuum. The thermal source is followed by a Zeeman slower with a single-layer coil of variable winding pitch. The single-layer design is simple to construct and has low inductance which allows for rapid switching of the magnetic field. The coil pitch was determined by fitting the analytic form of the magnetic field for a variable winding pitch to the desired magnetic field profile required to slow atoms. The measured magnetic field for the constructed coil is in excellent agreement with the desired field. The source produces atoms at 35 m/s with a flux up to 2 × 10 10 cm − 2 s − 1 at 200 ° C .
@article{bell_slow_2010, title = {{A} slow atom source using a collimated effusive oven and a single-layer variable pitch coil Zeeman slower}, volume = {81}, issn = {0034-6748, 1089-7623}, url = {http://scitation.aip.org/content/aip/journal/rsi/81/1/10.1063/1.3276712}, doi = {10.1063/1.3276712}, abstract = {We describe a simple slow atom source for loading a rubidiummagneto-optical trap. The source includes an effusive oven with a long heated collimation tube. Almost all components are standard vacuum parts. The heating elements and thermocouples are external to the vacuum, protecting them from the hostile hot alkali environment and allowing repair without breaking vacuum. The thermal source is followed by a Zeeman slower with a single-layer coil of variable winding pitch. The single-layer design is simple to construct and has low inductance which allows for rapid switching of the magnetic field. The coil pitch was determined by fitting the analytic form of the magnetic field for a variable winding pitch to the desired magnetic field profile required to slow atoms. The measured magnetic field for the constructed coil is in excellent agreement with the desired field. The source produces atoms at 35 m/s with a flux up to 2 × 10 10 cm − 2 s − 1 at 200 ° C .}, number = {1}, urldate = {2016-01-04TZ}, journal = {Review of Scientific Instruments}, author = {Bell, S. C. and Junker, M. and Jasperse, M. and Turner, L. D. and Lin, Y.-J. and Spielman, I. B. and Scholten, R. E.}, month = jan, year = {2010}, keywords = {Atom trapping, Atomic and molecular beams, Coils, Zeeman effect, magnetic fields}, pages = {013105} }
2009
- Mode stability of external cavity diode lasers,
S. D. Saliba, M. Junker, L. D. Turner, and R. E. Scholten.
Applied Optics 48, 6692 (2009).
[DOI] [Bibtex] [Abstract]
Mode stability is an important performance characteristic of external cavity diode lasers (ECDLs). It has been well established that the continuous mode-hop-free tuning range of a grating-feedback ECDL can be optimized by rotating the grating about a specific pivot location. We show that similar results can be obtained for other more convenient pivot locations by choosing instead the cavity length and grating location. The relative importance of the temperature stability of the diode and of the external cavity is also evaluated. We show that mechanically simple ECDL designs, using mostly standard components, can readily achieve a 35 GHz mode-hop-free tuning range at 780 nm.
@article{saliba_mode_2009, title = {Mode stability of external cavity diode lasers}, volume = {48}, issn = {0003-6935, 1539-4522}, url = {https://www.osapublishing.org/abstract.cfm?URI=ao-48-35-6692}, doi = {10.1364/AO.48.006692}, abstract = {Mode stability is an important performance characteristic of external cavity diode lasers (ECDLs). It has been well established that the continuous mode-hop-free tuning range of a grating-feedback ECDL can be optimized by rotating the grating about a specific pivot location. We show that similar results can be obtained for other more convenient pivot locations by choosing instead the cavity length and grating location. The relative importance of the temperature stability of the diode and of the external cavity is also evaluated. We show that mechanically simple ECDL designs, using mostly standard components, can readily achieve a 35 GHz mode-hop-free tuning range at 780 nm.}, number = {35}, urldate = {2016-01-04TZ}, journal = {Applied Optics}, author = {Saliba, Sebastian D. and Junker, Mark and Turner, Lincoln D. and Scholten, Robert E.}, month = dec, year = {2009}, pages = {6692} }
Honours Theses
- Michael Kewming, Quantum state tomography of an evolving spin-1 Bose gas, 2016.
- Prasanna Pakkiam, Towards Magnetic Resonance Imaging of Bose-Einstein Condensates, 2014.
- Sam Fischer, Magnon dispersion in ferromagnetic spinor Bose-Einstein condensates, 2014.
- Andrew Duong, Magnetic Gradiometry using Spinor Bose-Einstein Condensates, 2014.
- Vlad Negnevitsky BE(Hons), FPGA-based laser stabilisation using modulation transfer spectroscopy, 2010.
- Alexander Wood, A rubidium cold atom beam source, 2010.
- Christopher Watkins BE(Hons), Simulating Non-Adiabatic Spin Transitions, 2010.
- Philip Starkey, An optical, experiment control and data acquisition system for a BEC lab, 2010.
- Lisa Bennie, A large atom number magneto-optical trap for BEC production, 2010.
- Christopher Watkins, Direct Monte Carlo Simulation Forced Evaporative Cooling, 2010.
- Vlad Negnevitsky, Modulation transfer spectroscopy for fast, accurate laser stabilisation, 2009.