Actively stabilized wavelength-insensitive carrier elimination from an electro-optically modulated laser beam

Cooper, Nathan; Bateman, James; Dunning, Alexander; Freegarde, Tim

doi:10.1364/josab.29.000646

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…We control the EOM phase and frequency using an in-phase and quadrature-phase (IQ) modulator, fed from a pair of arbitrary waveform generators. The carrier wave is removed after the EOM using a polarizing beamsplitter cube [20], and temperature-dependent birefringence within the EOM is countered by active feedback to a liquid crystal phase retarder [21]. The remaining offresonant sideband is removed using a stabilized fibre-optic Mach-Zehnder interferometer [22].…”

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Interferometric Laser Cooling of Atomic Rubidium

et al. 2015

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We report the 1-D cooling of 85 Rb atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. Using stimulated Raman transitions between ground hyperfine states, 12 cycles of the interferometer sequence cool a freely-moving atom cloud from 21 µK to 3 µK. This pulsed analog of continuous-wave Doppler cooling is effective at temperatures down to the recoil limit; with augmentation pulses to increase the interferometer area, it should cool more quickly than conventional methods, and be more suitable for species that lack a closed radiative transition.The laser cooling of atomic gases has revolutionized experimental atomic physics [1] and raised the prospect of a range of atomic quantum technologies [2,3]. However, traditional Doppler cooling [4,5] relies upon the velocity-dependence of a single narrow radiative transition, and spontaneous emission to reset the atomic state. The cooling force is limited to a half photon-impulse per excited-state lifetime and, as many impulses are needed, requires a transition that can be closed by a few repump lasers. Doppler cooling has thus so far been limited to a handful of atomic elements and molecules [6][7][8][9].In [10], Weitz and Hänsch proposed a mechanism that could extend laser cooling to a wider range of species, by replacing the continuous wave (CW) excitation of conventional Doppler cooling with the broadband laser pulses of Ramsey matter-wave interferometry, and interleaving inversion pulses to eliminate the dependence upon the internal state energies. The interference signal, and hence the impulse imparted, were thus determined only by the particle's kinetic energy; manifold transitions could be accessed and, while spontaneous emission remained the entropy-removing mechanism, various schemes [11][12][13] could increase the impulse per spontaneous event. With a drive towards efficient pulsed schemes for molecular cooling [14][15][16] supported by improved mode-locked laser technologies, interferometric cooling appears a promising and flexible tool.The idea of a pulsed Ramsey analog to CW Doppler cooling has until now remained untested. In this letter, we report the first experimental demonstration of 1-D interferometric cooling of a cloud of already ultracold Rb atoms. Our long-lived quasi-two-level system, comprising the two 5S 1/2 ground hyperfine states of 85 Rb between which we drive stimulated Raman transitions, in principle allows cooling to the recoil limit, and we show that with just 12 cycles of the interferometric cooling sequence the atom cloud is cooled from 21 ± 2 µK to 3.2 ± 0.4 µK. Relaxation after each cycle is achieved by rapid pumping and decay of the single-photon 5S 1/2 -5P 3/2 transition, and the cooling rate is therefore limited mainly by the time needed for interferometric resolution of the different velocity classes.The Raman interferometric cooling mechanism is as follows. Two π/2 laser pulses, separated by a dwell time τ , act upon a two-level atom |Ψ = c 1 |1 + c 2 |2 as the beamsplitter and combiner of a R...

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confidence: 99%

Interferometric Laser Cooling of Atomic Rubidium

et al. 2015

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“…We modulate the EOM phase and frequency using an in-phase and quadrature-phase (IQ) modulator, fed from a pair of arbitrary waveform generators. The carrier wave at the output of the EOM is removed using a polarising beamsplitter cube [49], and temperature-dependent birefringence within the EOM is countered by active feedback to a liquid crystal phase retarder [50]. The remaining off-resonant sideband is removed using a stabilized fibreoptic Mach-Zehnder interferometer [51].…”

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confidence: 99%

Composite pulses for interferometry in a thermal cold atom cloud

et al. 2014

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Atom interferometric sensors and quantum information processors must maintain coherence while the evolving quantum wavefunction is split, transformed and recombined, but suffer from experimental inhomogeneities and uncertainties in the speeds and paths of these operations. Several error-correction techniques have been proposed to isolate the variable of interest. Here we apply composite pulse methods to velocity-sensitive Raman state manipulation in a freely-expanding thermal atom cloud. We compare several established pulse sequences, and follow the state evolution within them. The agreement between measurements and simple predictions shows the underlying coherence of the atom ensemble, and the inversion infidelity in an 80 micro-Kelvin atom cloud is halved. Composite pulse techniques, especially if tailored for atom interferometric applications, should allow greater interferometer areas, larger atomic samples and longer interaction times, and hence improve the sensitivity of quantum technologies from inertial sensing and clocks to quantum information processors and tests of fundamental physics

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“…The mass production of units such as the Arduino line of microcontrollers has helped to greatly reduce these hurdles. As a result, these units are showing up in an ever increasing variety of applications: from a low-cost controller for beam steering in optics [9], to the active electro-modulation of a laserʼs phase [10], to projects as diverse as the autonomous control of a robotic car [11] or even sending text messages through chemical signals [12].…”

Section: Microprocessor Technologymentioning

confidence: 99%

Rapid feedback control and stabilization of an optical tweezers with a budget microcontroller

2014

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Laboratories ranging the scientific disciplines employ feedback control to regulate variables within their experiments, from the flow of liquids within a microfluidic device to the temperature within a cell incubator. We have built an inexpensive, yet fast and rapidly deployed, feedback control system that is straightforward and flexible to implement from a commercially available Arduino Due microcontroller. This is in comparison with the complex, time-consuming and often expensive electronics that are commonly implemented. As an example of its utility, we apply our feedback controller to the task of stabilizing the main trapping laser of an optical tweezers. The feedback controller, which is inexpensive yet fast and rapidly deployed, was implemented from hacking an open source Arduino Due microcontroller. Our microcontroller based feedback system can stabilize the laser intensity to a few tenths of a per cent at 200 kHz, which is an order of magnitude better than the laserʼs base specifications, illustrating the utility of these devices.

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Actively stabilized wavelength-insensitive carrier elimination from an electro-optically modulated laser beam

Cited by 6 publications

References 13 publications

Interferometric Laser Cooling of Atomic Rubidium

Interferometric Laser Cooling of Atomic Rubidium

Composite pulses for interferometry in a thermal cold atom cloud

Rapid feedback control and stabilization of an optical tweezers with a budget microcontroller

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