Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1304.2527 · New Journal of Physics

Extreme spin squeezing for photons

Morgan W Mitchell, Federica A. Beduini

Published Jul 17, 2014• 10 citations
arXivHTMLPDF

Abstract

We apply spin-squeezing techniques to identify and quantify highly multi-partite photonic entanglement in polarization-squeezed light. We consider a practical single-mode scenario, and find that Wineland-criterion polarization squeezing implies entanglement of a macroscopic fraction of the total photons. A Glauber-theory computation of the observable N -photon density matrix, with N up to 100, finds that N -partite entanglement is observable despite losses and without post-selection. Genuine multi-partite entanglement up to at least is similarly confirmed. The preparation method can be made intrinsically permutation-invariant, allowing highly efficient state reconstruction. In this scenario, generation plus detection requires experimental resources, in stark contrast to the typical exponential scaling. We estimate existing detectors could observe 1000-partite entanglement from a few dB of polarization squeezing.

DOI
10.1088/1367-2630/16/7/073027

Related papers

Optical Spin Squeezing: Bright Beams as High-Flux Entangled Photon Sources

Federica A. Beduini, Morgan W. Mitchell

In analogy with the spin-squeezing inequality of Wang and Sanders [Phys. Rev. A 68, 012101 (2003)], we find inequalities describing macroscopic polarization correlations that are obeyed by all classical fields and whose violation implies entanglement of the photons that make up the optical beam. We consider a realistic and exactly solvable experimental scenario employing polarization-squeezed light from an optical parametric oscillator (OPO) and find polarization entanglement for postselected photon pairs separated by less than the OPO coherence time. The entanglement is robust against losses and extremely bright: efficiency can exceed that of existing "ultrabright" pair sources by at least an order of magnitude. This translation of spin-squeezing inequalities to the optical domain will enable direct tests of discrete-variable entanglement in a squeezed state.

arXiv:1303.5257•Physical Review Letters•Sep 30, 2013•12 citations

Macroscopic Quantum State Analyzed Particle by Particle

Federica A. Beduini, Joanna A. Zielińska, Vito Giovanni Lucivero +2 more

Macroscopic quantum phenomena, e.g., superconductivity and squeezing, are believed to result from entanglement of macroscopic numbers of particles. We report the first direct study of this kind of entanglement: we use discrete quantum tomography to reconstruct the joint quantum state of photon pairs extracted from polarization-squeezed light. Our observations confirm several predictions from spin-squeezing theory [Beduini et al., Phys. Rev. Lett. 111, 143601 (2013)], including strong entanglement and entanglement of all photon pairs within the squeezing coherence time. This photon-by-photon analysis may give insight into other macroscopic many-body systems, e.g., photon Bose-Einstein condensates.

arXiv:1410.7079•Physical Review Letters•Mar 27, 2015•13 citations

Sensitive detection of entanglement in exciton-polariton condensates via spin squeezing

Jingyan Feng, Ebubechukwu O. Ilo-Okeke, Alexey N. Pyrkov +2 more

We propose a method of generating and detecting entanglement via spin squeezing in an exciton-polariton condensate. Spin squeezing is a sensitive detector of entanglement because any squeezing below shot noise implies entanglement. In our scheme, two polariton spin species are resonantly pumped, forming a particle number fluctuating effective spin. The naturally occurring nonlinear interactions between the polaritons produce an effective one-axis squeezing interaction, which drives the system toward a spin-squeezed state at steady-state. We investigate the squeezing level that is attainable at the steady state for realistic experimental parameters and show the favorable parameters for strong squeezing. The amount of squeezing tends to improve with larger pumping, due to the bosonic enhancement of the one-axis twisting Hamiltonian. Using number-fluctuating versions of the Wineland squeezing criterion and optimal spin inequalities, we show how multipartite entanglement can be detected.

Physical Review A•Jul 30, 2021•9 citations

Detection of multipartite entanglement in the vicinity of Dicke states with many excitations

Géza Tóth

We present methods for detecting entanglement around N-qubit Dicke states with N/2 excitations. In the first part of the paper we show that for large N these states have the smallest overlap possible with states without multi-partite entanglement. Thus these states are particulary well suited for experiments aimed to create and detect genuine multi-partite entanglement. We present fidelity-based entanglement witness operators for detecting multipartite entanglement around these states. In the second part of the paper we consider entanglement criteria, somewhat similar to spin squeezing, based on the moments or variances of the collective spin operators. We present both criteria detecting entanglement in general and criteria detecting only genuine multi-partite entanglement.

•Nov 25, 2005•0 citations

Detecting Multiparticle Entanglement of Dicke States

Bernd Lücke, J. Peise, Giuseppe Vitagliano +4 more

Recent experiments demonstrate the production of many thousands of neutral atoms entangled in their spin degrees of freedom. We present a criterion for estimating the amount of entanglement based on a measurement of the global spin. It outperforms previous criteria and applies to a wider class of entangled states, including Dicke states. Experimentally, we produce a Dicke-like state using spin dynamics in a Bose-Einstein condensate. Our criterion proves that it contains at least genuine 28-particle entanglement. We infer a generalized squeezing parameter of -11.4(5) dB.

arXiv:1403.4542•Physical Review Letters•Apr 17, 2014•245 citations

Entanglement and extreme spin squeezing of unpolarized states

Giuseppe Vitagliano, Iagoba Apellaniz, Matthias Kleinmann +3 more

We present criteria to detect the depth of entanglement in macroscopic ensembles of spin- j particles using the variance and second moments of the collective spin components. The class of states detected goes beyond traditional spin-squeezed states by including Dicke states and other unpolarized states. The criteria derived are easy to evaluate numerically even for systems of very many particles and outperform past approaches, especially in practical situations where noise is present. We also derive analytic lower bounds based on the linearization of our criteria, which make it possible to define spin-squeezing parameters for Dicke states. In addition, we obtain spin squeezing parameters also from the condition derived in (Sørensen and Mølmer 2001 Phys. Rev. Lett. 86 4431 ). We also extend our results to systems with fluctuating number of particles.

arXiv:1605.07202•New Journal of Physics•Jan 20, 2017•31 citations
We apply spin-squeezing techniques to identify and quantify highly multi-partite photonic entanglement in polarization-squeezed light. We consider a practical single-mode scenario, and find that Wineland-criterion polarization squeezing implies entanglement of a macroscopic fraction of the total photons. A Glauber-theory computation of the observable N -photon density matrix, with N up to 100, finds that N -partite entanglement is observable despite losses and without post-selection. Genuine multi-partite entanglement up to at least is similarly confirmed. The preparation method can be made intrinsically permutation-invariant, allowing highly efficient state reconstruction. In this scenario, generation plus detection requires experimental resources, in stark contrast to the typical exponential scaling. We estimate existing detectors could observe 1000-partite entanglement from a few dB of polarization squeezing.
In analogy with the spin-squeezing inequality of Wang and Sanders [Phys. Rev. A 68, 012101 (2003)], we find inequalities describing macroscopic polarization correlations that are obeyed by all classical fields and whose violation implies entanglement of the photons that make up the optical beam. We consider a realistic and exactly solvable experimental scenario employing polarization-squeezed light from an optical parametric oscillator (OPO) and find polarization entanglement for postselected photon pairs separated by less than the OPO coherence time. The entanglement is robust against losses and extremely bright: efficiency can exceed that of existing "ultrabright" pair sources by at least an order of magnitude. This translation of spin-squeezing inequalities to the optical domain will enable direct tests of discrete-variable entanglement in a squeezed state.
Macroscopic quantum phenomena, e.g., superconductivity and squeezing, are believed to result from entanglement of macroscopic numbers of particles. We report the first direct study of this kind of entanglement: we use discrete quantum tomography to reconstruct the joint quantum state of photon pairs extracted from polarization-squeezed light. Our observations confirm several predictions from spin-squeezing theory [Beduini et al., Phys. Rev. Lett. 111, 143601 (2013)], including strong entanglement and entanglement of all photon pairs within the squeezing coherence time. This photon-by-photon analysis may give insight into other macroscopic many-body systems, e.g., photon Bose-Einstein condensates.
We propose a method of generating and detecting entanglement via spin squeezing in an exciton-polariton condensate. Spin squeezing is a sensitive detector of entanglement because any squeezing below shot noise implies entanglement. In our scheme, two polariton spin species are resonantly pumped, forming a particle number fluctuating effective spin. The naturally occurring nonlinear interactions between the polaritons produce an effective one-axis squeezing interaction, which drives the system toward a spin-squeezed state at steady-state. We investigate the squeezing level that is attainable at the steady state for realistic experimental parameters and show the favorable parameters for strong squeezing. The amount of squeezing tends to improve with larger pumping, due to the bosonic enhancement of the one-axis twisting Hamiltonian. Using number-fluctuating versions of the Wineland squeezing criterion and optimal spin inequalities, we show how multipartite entanglement can be detected.
We present methods for detecting entanglement around N-qubit Dicke states with N/2 excitations. In the first part of the paper we show that for large N these states have the smallest overlap possible with states without multi-partite entanglement. Thus these states are particulary well suited for experiments aimed to create and detect genuine multi-partite entanglement. We present fidelity-based entanglement witness operators for detecting multipartite entanglement around these states. In the second part of the paper we consider entanglement criteria, somewhat similar to spin squeezing, based on the moments or variances of the collective spin operators. We present both criteria detecting entanglement in general and criteria detecting only genuine multi-partite entanglement.
Recent experiments demonstrate the production of many thousands of neutral atoms entangled in their spin degrees of freedom. We present a criterion for estimating the amount of entanglement based on a measurement of the global spin. It outperforms previous criteria and applies to a wider class of entangled states, including Dicke states. Experimentally, we produce a Dicke-like state using spin dynamics in a Bose-Einstein condensate. Our criterion proves that it contains at least genuine 28-particle entanglement. We infer a generalized squeezing parameter of -11.4(5) dB.
We present criteria to detect the depth of entanglement in macroscopic ensembles of spin- j particles using the variance and second moments of the collective spin components. The class of states detected goes beyond traditional spin-squeezed states by including Dicke states and other unpolarized states. The criteria derived are easy to evaluate numerically even for systems of very many particles and outperform past approaches, especially in practical situations where noise is present. We also derive analytic lower bounds based on the linearization of our criteria, which make it possible to define spin-squeezing parameters for Dicke states. In addition, we obtain spin squeezing parameters also from the condition derived in (Sørensen and Mølmer 2001 Phys. Rev. Lett. 86 4431 ). We also extend our results to systems with fluctuating number of particles.