A5040344702- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Information and Cryptography
- Quantum optics and atomic interactions
- Advanced Frequency and Time Standards
- Mechanical and Optical Resonators
- Quantum Computing Algorithms and Architecture
- Quantum Mechanics and Applications
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Advanced MRI Techniques and Applications
- Advanced NMR Techniques and Applications
- Iron oxide chemistry and applications
- Acoustic Wave Resonator Technologies
- Electron Spin Resonance Studies
- Molecular spectroscopy and chirality
- Seismic Imaging and Inversion Techniques
Quside Technologies (Spain)
2019-2023
Institute of Photonic Sciences
2013-2020
Esteve (Spain)
2019-2020
Superposition, entanglement and non-locality constitute fundamental features of quantum physics. The fact that physics does not follow the principle local causality
We report the generation of a macroscopic singlet state in cold atomic sample via quantum nondemolition measurement-induced spin squeezing. observe 3 dB squeezing and detect entanglement with 5σ statistical significance using generalized spin-squeezing inequality. The degree implies at least 50% atoms have formed singlets.
We demonstrate a fast three-axis optical magnetometer using cold, optically trapped 87Rb gas as sensor. By near-resonant Faraday rotation we record the free-induction decay of spin polarized ensemble following to obtain three field components and one gradient component. A single measurement achieves shot-noise limited sub-nT sensitivity in 1 ms, with transverse spatial resolution ∼20 μm. make detailed analysis shot-noise-limited sensitivity.
We extend the covariance matrix description of atom–light quantum interfaces, originally developed for real and effective spin-1/2 atoms, to include 'spin alignment' degrees freedom. This allows accurate modelling optically probed spin-1 ensembles in arbitrary magnetic fields. also technical noise terms that are very common experimental situations. These field noise, variable atom number effect inhomogeneities. demonstrate validity our extended model by comparing numerical simulations a...
We apply entropy removal by measurement and feedback to a cold atomic spin ensemble. Using quantum nondemolition probing Faraday rotation measurement, weak optical pumping, we drive the initially random collective variable $\stackrel{^}{\mathbf{F}}$ toward origin $\stackrel{^}{\mathbf{F}}=\mathbf{0}$. use input-output relations ensemble noise models describe this control process identify an optimal two-round procedure. observe 12 dB of reduction, or factor-of-63 reduction in phase-space...
We demonstrate a new technique for detecting the amplitude of arbitrarily chosen components radio-frequency waveforms based on stroboscopic backaction evading measurements. combine quantum nondemolition measurements and probing to detect waveform with magnetic sensitivity beyond standard limit. Using an ensemble 1.5×10^{6} cold rubidium atoms, we entanglement-enhanced sensing sinusoidal linearly chirped waveforms, 1.0(2) 0.8(3) dB metrologically relevant noise reduction, respectively....
We study nonlinear interferometry applied to a measurement of atomic spin and demonstrate sensitivity that cannot be achieved by any linear-optical with the same experimental resources. use alignment-to-orientation conversion, nonlinear-optical technique from optical magnetometry, perform nondestructive alignment cold $^{87}$Rb ensemble. observe state-of-the-art in single-pass measurement, good agreement covariance-matrix theory. Taking degree measurement-induced squeezing as figure merit,...
We introduce an entanglement-depth criterion optimized for planar quantum-squeezed (PQS) states. It is connected with the sensitivity of such states estimating a phase generated by rotations about axis orthogonal to its polarization. compare numerically our well-known extreme spin-squeezing condition S\o{}rensen and M\o{}lmer [Phys. Rev. Lett. 86, 4431 (2001)] show that detects higher depth entanglement when both spin variances are squeezed below standard quantum limit. employ theory monitor...
We study the generation of planar quantum squeezed (PQS) states by nondemolition (QND) measurement an ensemble ^{87}Rb atoms with a Poisson distributed atom number. Precise calibration QND allows us to infer conditional covariance matrix describing F_{y} and F_{z} components PQS states, revealing dual squeezing characteristic states. have been proposed for single-shot phase estimation without prior knowledge likely values phase. show that arbitrary phase, generated can give metrological...
We describe a comagnetometer employing the f=1 and f=2 ground state hyperfine manifolds of ^{87}Rb spinor Bose-Einstein condensate as colocated magnetometers. The feature nearly opposite gyromagnetic ratios thus sum their precession angles is only weakly coupled to external magnetic fields, while being highly sensitive any effect that rotates both in same way. transverse magnetizations azimuth are independently measured by nondestructive Faraday rotation probing, we demonstrate 44.0(8) dB...
We demonstrate high-efficiency, shot-noise-limited differential photodetection with real-time signal conditioning, suitable for feedback-based quantum control of atomic systems. The detector system has efficiency 0.92, is from 7.4×105 to 3.7×108 photons per pulse, and provides voltage-encoded output at up 2.3 M pulses second.
We demonstrate an ultra-sensitive, non-destructive nonlinear measurement of atomic spin, with absolute sensitivity 9 dB beyond the best comparable linear measurement, and observe measurement-induced spin squeezing, confirming a central prediction quantum metrology.
We present interferometeric measurements of the $f=1$ to $f=2$ interhyperfine scattering lengths in a single-domain spinor Bose-Einstein condensate $^{87}\mathrm{Rb}$. The interaction leads strong and state-dependent modification spin-mixing dynamics with respect noninteracting description. employ hyperfine-specific Faraday-rotation probing reveal evolution transverse magnetization each hyperfine manifold for different state preparations, comagnetometer strategy cancel laboratory magnetic...
We report certified quantum non-demolition measurement of atomic spins using criteria developed for continuous variable experiments in optics. observe state preparation and information–damage trade–off beyond classical limits by seven twelve standard deviations.
We report an experimental study of a new technique for spin cooling ensemble ultracold atoms via quantum non-demolition (QND) measurement and incoherent feedback. have demonstrated 12db noise reduction. This has direct application in generating highly entangled macroscopic singlet state.
We report an experimental study of a new technique for spin cooling ensemble ultracold atoms via quantum non-demolition (QND) measurement and incoherent feedback. have demonstrated 12db noise reduction. This has direct application in generating highly entangled macroscopic singlet states.
We describe experimental generation of states simultaneously squeezed in two collective spin components by quantum non-demolition measurement. These "planar states" improve phase estimation at all rotation angles.
We extend the covariance-matrix description of atom-light quantum interfaces to spin-1 systems including technical noise and decoherences. use this predict produce a planar squeezed state in cold 87Rb ensemble.