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We report an experimental study of a new technique for spin cooling an ensemble of ultracold atoms via quantum non-demolition (QND) measurement and incoherent feedback. We have demonstrated 12db spin noise reduction. This technique has direct application in generating highly entangled macroscopic singlet states.
We report certified quantum non-demolition measurement of atomic spins using criteria developed for continuous variable experiments in optics. We observe quantum state preparation and information-damage trade-off beyond classical limits by seven and twelve standard deviations.
We report on a fast, nondestructive and sensitive measurement technique that uses atomic spin precession and non-destructive Faraday rotation probing to measure all three components of the magnetic field with kHz bandwidth. In contrast to other vector magnetometer techniques that modulate an applied magnetic field [1, 2, 3] we modulate the initial atomic polarization and extract the magnetic field...
Techniques for making quantum-limited nonlinear measurements have attracted a great deal of recent attention because they allow a measurement sensitivity that improves as the number of measuring particles (e.g. photons) increases faster than an equivalent linear measurement. This super-Heisenberg scaling was recently demonstrated in a proof-of-principle experiment [1], in which a measurement Hamiltonian...
We report an experimental study of a new technique for spin cooling an ensemble of ultracold atoms via quantum non-demolition (QND) measurement and incoherent feedback. This is a form of entropie cooling of the spins that increases the phase space density, in contrast to coherent feedback schemes such as described in Refs.[l, 2]. Our technique has potential applications in quantum optics such as quantum...
We extend the covariance-matrix description of atom-light quantum interfaces to spin-1 systems including technical noise and decoherences. We use this description to predict and produce a planar squeezed state in a cold 87Rb ensemble.
We report a nonlinear alignment-to-orientation conversion measurement of atomic spins that simultaneously shows super-Heisenberg scaling and achieves projection-noise limited sensitivity of 990 spins, 20 dB more sensitive than the previous best nonlinear measurement. Using this technique, we have recently demonstrated conditional spin squeezing of the atomic ensemble, and entanglement-enhanced measurement...
We report an experimental study of a new technique for entropic cooling of the spin in an ensemble of ultracold atoms via quantum non-demolition (QND) measurement and incoherent feedback.
We demonstrate spin squeezing and entanglement in a large-spin system via quantum non-demolition measurement. We make non-destructive, projection-noise-limited collective spin measurements on an ensemble of up to in 8.4 × 105 laser-cooled 87Rb atoms in the f = 1 hyperfine ground state. A dynamically-decoupled probing scheme [Phys. Rev. Lett. 105, 093602 (2010)] prevents probe-induced decoherence....
Quantum metrology studies the use of entanglement and other quantum resources to improve precision measurement. An interferometer using N independent particles to measure a parameter χ can achieve at best the “standard quantum limit” (SQL) of sensitivity δ χ ∝ N−1/2. The same interferometer using N entangled particles can achieve in principle the “Heisenberg limit” δ χ ∝ N−1, using exotic states,...
Atom-mediated optical nonlinearities, generated within an atom-light quantum interface, allow spin measurement with sensitivity that scales better than the Heisenberg limit. This demonstrates interactions as a new resource for quantum metrology.
We demonstrate spin squeezing of a magnetically sensitive coherent spin-state in an ensemble of ~ 6.5 × 105 cold 87Rb atoms. Quantum non-demolition measurements achieved a spin-noise reduction by 2.9(+1.3-1.0) dB compared to the initial projection noise level.
Atomic ensembles have gained a lot of interest in the last decade for their prospective use as quantum memories, in precision measurements and other applications in quantum information processing. The atomic part of the interface presented here is an all-optically trapped atomic ensemble of 87Rb at a temperature of 25 muK. The ensemble consists of 106 atoms and has an elongated shape with an aspect...
This work considers an atom-light interface consisting of pulses of polarized light that interacts with an ensemble of 106 cold 87Rb in dipole trap. Measurements of polarization changes in the light is used in probing the atomic state. In such polarization-based atom-light interface, a Hamiltonian nonlinear in the Stokes operators can be produced through optical nonlinearities. This work investigates...
We use narrow-band quantum light sources, tuned to the rubidium D1 resonance, to produce polarization-squeezed and polarization-NooN states for Heisenberg-limited measurements on atoms. By paramagnetic Faraday rotation these states measure the atomic spin polarization.
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