Why momentum width matters for atom interferometry with Bragg pulses

Szigeti, Stuart S.; Debs, J. E.; Hope, Joseph; Robins, Nicholas; Close, John

doi:10.1088/1367-2630/14/2/023009

Cited by 139 publications

(157 citation statements)

References 30 publications

Supporting

Mentioning

156

Contrasting

Order By: Relevance

“…We find that shorter pulse durations limit the effects of off-resonant coupling, which is in agreement with the results of Ref. [177] where the efficiency of transfer over a broad momentum width is found to decrease with pulse duration. It is also clear in Fig.…”

Section: C6 Impact Of Realistic Bragg Pulses On Distinguishabilitysupporting

confidence: 92%

“…Fffects due to off-resonant coupling play a key role in Chapters 4 and 5 and have previously been qualitatively studied in Ref. [177] in the context of atom interferometry. We illustrate the effect of coupling between off-resonant modes in Fig.…”

Section: B2 Analytic Solution Of Bragg Pulse Transformationmentioning

confidence: 99%

“…Ref. [177]) to give the transmission and reflection amplitudes of the pulses, and is a reasonably valid approximation to the Gaussian Bragg pulses used in numerical simulations. To compare directly we note that square and Gaussian Bragg pulses of the same lattice depth and of duration τ and τ respectively are related by the equivalence relation τ = √ 2πτ .…”

mentioning

confidence: 99%

See 2 more Smart Citations

Ultracold atoms for foundational tests of quantum mechanics

Lewis-Swan¹

View full text Add to dashboard Cite

We investigate the generation, characterization and measurement of non-classical correlations and entanglement in ultracold atomic gases. Specifically, we propose new tests to demonstrate non-classical correlations, Einstein-Podolsky-Rosen (EPR) entanglement and Bell inequality violations, in systems involving dilute gas Bose-Einstein condensates (BECs). We focus on the challenges of generating and preserving these correlations in atom-optics schemes with massive particles and define appropriate operational measurements to demonstrate them experimentally. Further, we characterize how measures of EPR entanglement and violations of a Bell inequality evolve with time and scale with system size.To begin, we detail a theoretical proposal to demonstrate the well-known optical HongOu-Mandel (HOM) effect of destructive quantum interference with massive particles. Our proposed matter-wave experiment, realized recently in a related experimental setup [Lopes et. al., Nature 520, 66 (2015)], utilizes pair-correlated atoms produced via spontaneous fourwave mixing in colliding BECs. The atom pairs are then subjected to Bragg pulses -the atom-optics equivalent of optical mirrors and beam-splitters -to realize a HOM atom interferometer. By taking advantage of the multimode nature of the four-wave mixing process we formulate a measurement protocol which, unlike the optical case, does not require repeated measurements for different beam-splitter settings. We perform numerical simulations of a realistic experimental system and predict a HOM 'dip' visibility of ∼ 69%, indicating the correlations between atom pairs are stronger than classically allowed.In Chapter 5 we outline a theoretical proposal to demonstrate a violation of a motionalstate Bell inequality with massive particles. Identically to Chapter 4, the proposal uses pairs of momentum-entangled atoms produced via spontaneous four-wave mixing in colliding BECs. However, this scheme requires two pairs of atoms which are used as the input state of an atom-optics analog of the Rarity-Tapster interferometer, constructed via a sequence of Bragg pulses. We formulate a measurable form of the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality taking into account experimental limitations, and perform numerical simulations of a realistic experimental system for a range of parameters. We predict values of the CHSH-Bell parameter up to S 2.5, demonstrating a violation of the CHSH-Bell inequality which is bounded by S ≤ 2 for local hidden-variable theories.In Chapter 6 we investigate the prospect of demonstrating EPR entanglement between massive particles via spin-changing collisions in a spinor BEC. This investigation is motivated by recent experimental work of Gross et al. [Nature 480, 219 (2011)] who reported inconclusive results in an attempt to measure EPR entanglement. In the experiment, spinchanging collisions between atoms in the (F, m F ) = (2, 0) state lead to pairs of strongly correlated atoms being created in opposing (F, m F ) = (2, ±1) states. For m F = ±1 states in...

show abstract

Section: C6 Impact Of Realistic Bragg Pulses On Distinguishabilitysupporting

confidence: 92%

Section: B2 Analytic Solution Of Bragg Pulse Transformationmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Ultracold atoms for foundational tests of quantum mechanics

Lewis-Swan¹

View full text Add to dashboard Cite

show abstract

“…The spin superposition in combination with the large spatial coherence of the BEC allows simultaneous precision measurement of gravity and absolute magnetic field gradient in an unsheilded device [23]. A 2 × 10 6 atom condensate is used in the interferometer [24] with no loss in contrast over all interferometer times.The experimental schematic is shown in Figure 1. A hot sample of 87 Rb atoms is created and precooled in a 2D magneto-optical trap (MOT).…”

mentioning

confidence: 99%

Simultaneous Precision Gravimetry and Magnetic Gradiometry with a Bose-Einstein Condensate: A High Precision, Quantum Sensor

et al. 2016

View full text Add to dashboard Cite

A Bose-Einstein condensate is used as an atomic source for a high precision sensor. A 5 × 10 6 atom F=1 spinor condensate of 87 Rb is released into free fall for up to 750 ms and probed with a T = 130 ms Mach-Zehnder atom interferometer based on Bragg transitions. The Bragg interferometer simultaneously addresses the three magnetic states, |m f = 1, 0, −1 , facilitating a simultaneous measurement of the acceleration due to gravity with a 1000 run precision of ∆g/g= 1.45 × 10 −9 and the magnetic field gradient to a precision 120 pT/m.Acquiring accurate and precise data on magnetic and gravity fields is critical to progress in mineral discovery [1,2] Like their classical counterparts, sensors based on cold atoms measure the trajectory of the test particles [19]. Unlike classical particles, atoms offer internal degrees of freedom, allowing for the possibility of additional simultaneous measurements including time, magnetic fields and magnetic field gradients. Although these advantages are intrinsic to all atomic sources, ultra-cold BoseEinstein condensates (BEC) offer additional benefits over thermal atoms. An intrinsic feature of a BEC is a spatial coherence equivalent to the size of the cloud which is generally 100's of µm while thermal sources have spatial coherence length on the order of the de Broglie wavelength,mk B T (∼ 0.1µm). This spatial coherence has been shown to provide robustness to systematics which result in loss of fringe contrast such as cloud mismatch at the final beam splitter pulse [20]. The BEC then allows a sensor to be operated unshielded in varying environments where background field gradients and curvatures are non-negligible.This letter introduces a new type of sensor which simultaneously measures gravity and magnetic field gradients to high precision. In this lab based sensor, an optically trapped cloud of 87 Rb atoms is cooled to condensation and projected into an F = 1 spin superposition, then passed through a vertical light pulse Mach-Zehnder interferometer based on Bragg transitions [21,22]. The spin superposition in combination with the large spatial coherence of the BEC allows simultaneous precision measurement of gravity and absolute magnetic field gradient in an unsheilded device [23]. A 2 × 10 6 atom condensate is used in the interferometer [24] with no loss in contrast over all interferometer times.The experimental schematic is shown in Figure 1. A hot sample of 87 Rb atoms is created and precooled in a 2D magneto-optical trap (MOT). These precooled atoms are transferred to an aluminum ultra-high vacuum cell via a high impedance gas flow line and blue detuned push beam. In 6 s, 5 × 10 9 atoms are collected in a 3D MOT where a standard compression and polarization gradient cooling sequence is applied achieving a 20 µK temperature. The atoms are then loaded into a hybrid magnetic quadropole and crossed optical dipole trap. An initial stage of evaporation is completed using a microwave knife over 4.5 s leaving 4×10 7 atoms at 4 µK and a phase space density of 1 × 10 −4 . The magne...

show abstract

“…The laser power required for Bragg transitions sharply increases with the diffraction order. 20,21 These high power lasers can be prepared by the secondharmonic generation (SHG) method. [22][23][24][25] The frequency difference between the two Bragg beams needs to be chirped to compensate for the Doppler shift occurring because of the free fall of the atoms.…”

Section: Introductionmentioning

confidence: 99%

Low-phase noise and high-power laser for Bragg atom interferometer

et al. 2017

View full text Add to dashboard Cite

We present a laser system with low-phase noise and an output power up to 8.8 W at 780 nm for driving Bragg transitions in a 87Rb fountain. An optical phase-locked loop (OPLL) is employed to restrain the phase noise that arises from the spatial separation of the two Bragg beams at low frequencies. The residual phase variance is suppressed by two orders around 400 Hz. A Mach-Zehnder Bragg atom interferometer, based on the four-photon recoil scheme, has been realized using this laser system. This interferometer shows a resolution of 5×10−9g at an integration time of 1200 s for gravity measurements.

show abstract

Why momentum width matters for atom interferometry with Bragg pulses

Cited by 139 publications

References 30 publications

Ultracold atoms for foundational tests of quantum mechanics

Ultracold atoms for foundational tests of quantum mechanics

Simultaneous Precision Gravimetry and Magnetic Gradiometry with a Bose-Einstein Condensate: A High Precision, Quantum Sensor

Low-phase noise and high-power laser for Bragg atom interferometer

Contact Info

Product

Resources

About