Open accessJournal Article

# Momentum Entanglement for Atom Interferometry.

05 Mar 2021-Physical Review Letters (International Society for Optics and Photonics)-Vol. 127, Iss: 14, pp 140402
Abstract: Compared to light interferometers, the flux in cold-atom interferometers is low and the associated shot noise large. Sensitivities beyond these limitations require the preparation of entangled atoms in different momentum modes. Here, we demonstrate a source of entangled atoms that is compatible with state-of-the-art interferometers. Entanglement is transferred from the spin degree of freedom of a Bose-Einstein condensate to well-separated momentum modes, witnessed by a squeezing parameter of -3.1(8) dB. Entanglement-enhanced atom interferometers open up unprecedented sensitivities for quantum gradiometers or gravitational wave detectors.

Topics: Atom interferometer (64%), Quantum entanglement (53%), Momentum (52%) ... read more
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8 results found

Open accessJournal Article
Abstract: Quantum entanglement has been generated and verified in cold-atom experiments and used to make atom-interferometric measurements below the shot-noise limit. However, current state-of-the-art cold-atom devices exploit separable (i.e., unentangled) atomic states. This perspective piece asks the question: can entanglement usefully improve cold-atom sensors, in the sense that it gives new sensing capabilities unachievable with current state-of-the-art devices? We briefly review the state-of-the-art in precision cold-atom sensing, focusing on clocks and inertial sensors, identifying the potential benefits entanglement could bring to these devices, and the challenges that need to be overcome to realize these benefits. We survey demonstrated methods of generating metrologically useful entanglement in cold-atom systems, note their relative strengths and weaknesses, and assess their prospects for near-to-medium term quantum-enhanced cold-atom sensing.

Topics: Quantum entanglement (54%)

10 Citations

Open accessJournal Article
Josep Cabedo1, J. Claramunt2, Alessio Celi1Institutions (2)
23 Sep 2021-Physical Review A
Abstract: In spinor Bose-Einstein condensates, spin-changing collisions are a remarkable proxy to coherently realize macroscopic many-body quantum states. These processes have been, e.g., exploited to generate entanglement, to study dynamical quantum phase transitions, and proposed for realizing nematic phases in atomic condensates. In the same systems dressed by Raman beams, the coupling between spin and momentum induces a spin dependence in the scattering processes taking place in the gas. Here we show that, at weak couplings, such modulation of the collisions leads to an effective Hamiltonian which is equivalent to the one of an artificial spinor gas with spin-changing collisions that are tunable with the Raman intensity. By exploiting this dressed-basis description, we propose a robust protocol to coherently drive the spin-orbit-coupled condensate into the ferromagnetic stripe phase via crossing a quantum phase transition of the effective low-energy model in an excited state.

Topics: , Spin-½ (59%), Quantum entanglement (57%) ... read more

2 Citations

Open accessPosted Content
Abstract: The stability of matter-wave sensors benefits from interrogating large-particle-number atomic ensembles at high cycle rates. The use of quantum-degenerate gases with their low effective temperatures allows constraining systematic errors towards highest accuracy, but their production by evaporative cooling is costly with regard to both atom number and cycle rate. In this work, we report on the creation of cold matter-waves using a crossed optical dipole trap and shaping it by means of an all-optical matter-wave lens. We demonstrate the trade off between residual kinetic energy and atom number by short-cutting evaporative cooling and estimate the corresponding performance gain in matter-wave sensors. Our method is implemented using time-averaged optical potentials and hence easily applicable in optical dipole trapping setups.

Topics: Dipole (52%), Lens (optics) (51%), Evaporative cooler (50%)

Open accessPosted Content
Abstract: We theoretically investigate how entangled atomic states generated via spin-changing collisions in a spinor Bose-Einstein condensate can be designed and controllably prepared for atom interferometry that is robust against common technical issues, such as limited detector resolution. We use analytic and numerical treatments of the spin-changing collision process to demonstrate that triggering the entangling collisions with a small classical seed rather than vacuum fluctuations leads to a more robust and superior sensitivity when technical noise is accounted for, despite the generated atomic state ideally featuring less metrologically useful entanglement. Our results are relevant for understanding how entangled atomic states are best designed and generated for use in quantum-enhanced matter-wave interferometry.

Topics: Quantum entanglement (53%), Atom interferometer (53%), Interferometry (51%) ... read more

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85 results found

Journal Article
Mark A. Kasevich1, Steven Chu1Institutions (1)
Abstract: The mechanical effects of stimulated Raman transitions on atoms have been used to demonstrate a matter-wave interferometer with laser-cooled sodium atoms. Interference has been observed for wave packets that have been separated by as much as 2.4 mm. Using the interferometer as an inertial sensor, the acceleration of a sodium atom due to gravity has been measured with a resolution of 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ after 1000 sec of integration time.

Topics: Atom interferometer (54%)

971 Citations

Journal Article
Norman F. Ramsey1Institutions (1)
15 Jun 1950-Physical Review
Abstract: A new molecular beam resonance method using separated oscillating fields at the incident and emergent ends of the homogeneous field region is theoretically investigated in this paper. An expression is obtained for the quantum mechanical transition probability of a system between two states when the system is subjected to such separated oscillating fields. This is numerically averaged over the molecular velocity distribution and provides the theoretical shape of the resonance curves. It is found that resonances with such a technique have a theoretical half-width only 0.6 as great as those by conventional molecular beam resonance methods. In addition to producing sharper resonance minima, the new method has its resonances much less broadened by inhomogeneities of the fixed field, it makes possible resonance experiments in regions into which an oscillating field cannot be introduced, and it is more convenient and effective with short wave-length radiation.

Topics: Resonance (58%), Molecular beam (56%), Field (physics) (54%) ... read more

788 Citations

Journal ArticleDOI: 10.1038/23655
Achim Peters1, Keng Yeow Chung1, Steven Chu1Institutions (1)
26 Aug 1999-Nature
Abstract: Laser-cooling of atoms and atom-trapping are finding increasing application in many areas of science1 One important use of laser-cooled atoms is in atom interferometers2 In these devices, an atom is placed into a superposition of two or more spatially separated atomic states; these states are each described by a quantum-mechanical phase term, which will interfere with one another if they are brought back together at a later time Atom interferometers have been shown to be very precise inertial sensors for acceleration3,4, rotation5 and for the measurement of the fine structure constant6 Here we use an atom interferometer based on a fountain of laser-cooled atoms to measure g, the acceleration of gravity Through detailed investigation and elimination of systematic effects that may affect the accuracy ofthe measurement, we achieve an absolute uncertainty of Δg/g ≈ 3 × 10−9, representing a million-fold increase in absoluteaccuracy compared with previous atom-interferometer experiments7 We also compare our measurement with the value of g obtained at the same laboratory site using a Michelson interferometer gravimeter (a modern equivalent of Galileo's ‘leaning tower’ experiment in Pisa) We show that the macroscopic glass object used in this instrument falls with the same acceleration, to within 7 parts in 109, as a quantum-mechanical caesium atom

Topics: Atom interferometer (66%), Gravimeter (55%),  ... read more

733 Citations

Open accessJournal Article
Christian Gross1, Tilman Zibold1, Eike Nicklas1, Jérôme Estève2  +2 moreInstitutions (2)
22 Apr 2010-Nature
Abstract: Interference is fundamental to wave dynamics and quantum mechanics. The quantum wave properties of particles are exploited in metrology using atom interferometers, allowing for high-precision inertia measurements. Furthermore, the state-of-the-art time standard is based on an interferometric technique known as Ramsey spectroscopy. However, the precision of an interferometer is limited by classical statistics owing to the finite number of atoms used to deduce the quantity of interest. Here we show experimentally that the classical precision limit can be surpassed using nonlinear atom interferometry with a Bose-Einstein condensate. Controlled interactions between the atoms lead to non-classical entangled states within the interferometer; this represents an alternative approach to the use of non-classical input states. Extending quantum interferometry to the regime of large atom number, we find that phase sensitivity is enhanced by 15 per cent relative to that in an ideal classical measurement. Our nonlinear atomic beam splitter follows the 'one-axis-twisting' scheme and implements interaction control using a narrow Feshbach resonance. We perform noise tomography of the quantum state within the interferometer and detect coherent spin squeezing with a squeezing factor of -8.2 dB (refs 11-15). The results provide information on the many-particle quantum state, and imply the entanglement of 170 atoms.

Topics: Quantum metrology (68%), Atom interferometer (67%), Quantum limit (64%) ... read more

690 Citations

Journal Article
Yvan Castin1, R. Dum1Institutions (1)
Abstract: We present analytical results for the macroscopic wave function of a Bose-Einstein condensate in a time dependent harmonic potential. The evolution of the spatial density is a dilatation, characterized by three scaling factors which allow a classical interpretation of the dynamics. This approach is an efficient tool for the analysis of recent experimental results on the expansion and collective excitation of a condensate.

Topics: , Wave function (50%)

645 Citations

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