A high-flux BEC source for mobile atom interferometers

Rudolph, Jan; Herr, Waldemar; Grzeschik, Christoph; Sternke, Tammo; Grote, Alexander; Popp, Manuel; Becker, Dennis; Müntinga, Hauke; Ahlers, Holger; Peters, A.; Lämmerzahl, Cláus; Sengstock, K.; Gaaloul, Naceur; Ertmer, W.; Rasel, Ernst M.

doi:10.1088/1367-2630/17/6/065001

Cited by 103 publications

(120 citation statements)

References 54 publications

(72 reference statements)

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“…Nonetheless, fast condensate production generally sacrifices total atom number for duty cycle. This is evident from the best integrated flux [32] achieved in fast devices, 2.5 × 10 5 atoms/s, when compared to the 4 × 10 5 atoms/s flux in this device. The application of techniques such as sideband cooling offer a path to improving flux on both atom chip and free-space based sensors [33] without sacrificing atom number.…”

Section: (B)mentioning

confidence: 64%

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

et al. 2016

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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...

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Section: (B)mentioning

confidence: 64%

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

et al. 2016

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“…Microwave fountain clocks, providing the realization of the SI second, are currently limited by the SQL. 22,[40][41][42] In combination with the recently developed sources of Bose-Einstein condensed atoms with small densities 43,44 and high repetition rates, 45 our results pave the way for the development of a new generation of atomic microwave clocks operating beyond the SQL.…”

Section: 39mentioning

confidence: 68%

0.75 atoms improve the clock signal of 10,000 atoms

et al. 2017

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Since the pioneering work of Ramsey, atom interferometers are employed for precision metrology, in particular to measure time and to realize the second. In a classical interferometer, an ensemble of atoms is prepared in one of the two input states, whereas the second one is left empty. In this case, the vacuum noise restricts the precision of the interferometer to the standard quantum limit (SQL). Here, we propose and experimentally demonstrate a novel clock configuration that surpasses the SQL by squeezing the vacuum in the empty input state. We create a squeezed vacuum state containing an average of 0.75 atoms to improve the clock sensitivity of 10, 000 atoms by 2.05−.37 dB. The SQL poses a significant limitation for today's microwave fountain clocks, which serve as the main time reference. We evaluate the major technical limitations and challenges for devising a next generation of fountain clocks based on atomic squeezed vacuum.

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“…This corresponds to a differential acceleration sensitivity of 1 × 10 −10 g per shot (5 × 10 −10 g= ffiffiffiffiffiffi Hz p given the 22 s cycle time) and is near the estimated shot noise limit of ∼1E per shot. Improvements in the atom source and imaging system would increase the atom number and contrast, allowing higher sensitivity, while a more advanced cold atom source [35] could reduce the cycle time to several seconds.…”

Section: Prl 118 183602 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%