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

Conference on Lasers and Electro-Optics

Spin squeezing in atomic systems

L. Vemac, M. Pinard, E. Giacobino

Published Aug 29, 2005• 0 citations
Publisher

Abstract

Summary form only given. In high-precision atomic experiments such as atomic interferometry, the accuracy is ultimately limited by the so-called quantum projection noise, due to the fact that the atoms are not in an eigenstate of the measured quantity. In an ensemble of N independent atoms, fluctuations proportional to N/sup -1/2/ result from this effect. A few years ago, it was shown that using squeezed atomic states would allow to reduce these fluctuations, in the same way as squeezed states of light allow to obtain noise reduction in measurements of the electromagnetic field.

DOI
10.1109/iqec.2000.907779

Related papers

Entanglement for Metrology with Atomic Ensembles

Eugene Simon Polzik

Ultimate quantum fluctuations which limit the fundamental precision in metrology can be only reduced by entanglement of particles. In particular, squeezing of the fluctuations called the spin projection noise by means of generation of entanglement in an ensemble of atoms can improve the precision of spectroscopy and of atomic clocks. A powerful tool for generation of multiparticle entanglement is a quantum nondemolition measurement (QND). We will describe the fundamentals of QND measurement of atomic collective state with light and present a recent experiment [1] where this method has been used to reduce the projection noise on the clock transition in an ensemble of 105 cold and trapped Cesium atoms. Another method for generation of spin squeezing via electron-nucleus entanglement applicable only for atoms with angular momentum higher than ½ will be also discussed [2].

Conference on Lasers and Electro-Optics•Jan 1, 2009•0 citations

Entanglement For Atom Interferometers

Alexander Idel

Quantum Sensors, like atom interferometers (AI), can be employed for high-precision measurements of inertial forces, including their application as gravimeters, gradiometers, accelerometers, and gyroscopes. Their measurement principle relies on ultracold atoms that are prepared in quantum-mechanical superposition states in external degrees of freedom. These states can be prepared by a momentum transfer of a Raman laser. Then the superposition state senses the effect of an inertial force, which induce a corresponding relative phase. The phase is read out by a final coupling which converts the interferometric phase into a atom number difference between the two states. The difference provides an estimate of the interferometric phase and the corresponding quantity of interest. The quantum mechanical noise of the atomic ensemble cause a fundamental uncertainty of this estimation, which I analyze for generic AIs. For small atomic densities, the quantum phase noise of the ensemble limits the interferometric sensitivity. For large densities, quantum number fluctuations generate density fluctuations, which generates phase noise. I show that these two competing effects result in an optimal atom number with a maximal interferometer resolution. Squeezed atomic samples allow for a reduction of the quantum noise of one quantity at the expense of an increased noise along of a conjugate quantity. Phase and number are such quantities which obey to a variant of Heisenberg’s uncertainty principle. Neither phase nor number squeezing can improve the maximal interferometer resolution. As one main result of this thesis, I show how an optimal squeezing in between number and phase squeezing, allows for a fundamental improvement. I evaluate possible experimental paths to implement the proposed protocol. Concepts for a squeezing-enhanced operation of external-degree AIs have not yet been demonstrated. I propose and implement an atomic gravimeter, which is designed to accept spin-squeezed atomic states as input states. The interferometer is designed such that the interferometer couplings are performed in spin space, while the phase accumulation is performed in momentum states. For this interferometer, the squeezed input can be directly obtained from spin dynamics in spinor Bose-Einstein condensates. The main noise contributions in the experiment are analyzed, which results in a factor of 84 above the relevant quantum limit, preventing a squeezing enhancement so far. I outline a suppression of the main noise source, uncontrolled AC Stark shift on the squeezed mode and propose future important applications, including test of spontaneous collapse theories and an improvement of large-scale, high-precision gradiometers.

•Jan 1, 2021•0 citations

IMPROVED ATOM COUNTING USING SQUEEZED LIGHT FOR ATOM INTERFEROMETRY APPLICATIONS

Vetere, Mark D.

Atom interferometer measurements are affected by the amount of quantum noise from the laser used to detect atoms. To improve the quantum limited sensitivity of interferometers, there needs to be a way to reduce the amount of quantum noise. Light is composed of two quadratures, where the product of the noise in each quadrature cannot be below a minimum threshold set by the Heisenberg Uncertainty Principle. However, the noise in one quadrature can be reduced at the expense of the other. This form of light is referred to as “squeezed light.” Squeezed light can be produced using four-wave mixing (FWM). Electromagnetically induced transparency (EIT) is an interference phenomenon that occurs when a three-level atom is driven by a coherent field that makes a non-linear medium transparent to the probing field and holds a great deal of similarities to FWM. This thesis developed a theoretical framework that describes the measurement of atomic states and associated noise when quantum light is used to drive the atom and lays the groundwork to produce squeezed light through developing an experiment to produce EIT, as well as discussing the similarities between EIT and FWM to create and further study FWM for improved atom interferometry.

•Jun 1, 2022•0 citations

Squeezing of atomic quantum projection noise

Patrick Windpassinger, Daniel Oblak, Ulrich B. Hoff +4 more

We provide a framework for understanding recent experiments on squeezing of a collective atomic pseudo-spin, induced by a homodyne measurement on off-resonant probe light interrogating the atoms. The detection of light decimates the atomic state distribution and we discuss the conditions under which the resulting reduced quantum fluctuations are metrologically relevant. In particular, we consider a dual probe scheme which benefits from a cancelation of classical common mode noise sources such that quantum fluctuations from light and atoms are the main contributions to the detected signal.

arXiv:0906.2572•Journal of Modern Optics•Jun 26, 2009•8 citations

Adiabaticity in state preparation for spin squeezing of large atom ensembles

Shenchao Jin, Han Bao, Junlei Duan +5 more

Spin-squeezed state is a many-body entangled state of great interest for precision measurements. Although the absolute sensitivity at the standard quantum limit is better for a larger atom number, the greater dominance of classical noises over atom projection noise makes it harder to achieve spin squeezing. Here, we show both theoretically and experimentally that adiabatic pulse control of the pump field in state preparation is indispensable to sufficient noise suppression, which is the prerequisite for spin squeezing. This technique is generally applicable to spin-squeezing experiments involving a large ensemble and is thus of significance for quantum metrology applications.

Photonics Research•Aug 10, 2021•11 citations

Complement 5A: Squeezed states of light: the reduction of quantum fluctuations

G. Grynberg, Alain Aspect, Claude Fabre +1 more

We showed in Section 5.2 of the present chapter that according to quantum theory the value of the electric field of an electromagnetic wave could not be predicted to arbitrarily high precision, this being a consequence of the uncertainty relation satisfied by the two quadrature components of the field (Equation 5.32), which imposed a finite limit on the product of their variances. This limit is more than an abstract theoretical limit; it is often the overriding factor determining the resolution of high-precision optical measurements. In such situations measurements by photodetectors on the field exhibit uncontrollable fluctuations of quantum origin known as quantum noise . Fortunately, as we shall show in this complement, it is possible to overcome this by using non-classical states of the radiation field, namely the squeezed states , provided measurements are made of a single one of a pair of conjugate field variables. A field mode prepared in such a state exhibits reduced quantum noise in one of the variables at the expense of increased noise in the other, so that the uncertainty relation involving their variances is still satisfied. The potential of such states for increasing the obtainable precision of optical measurements is self-evident. However, the practical realization of the potential benefits requires delicate experimental techniques that we describe only briefly here.

Cambridge University Press eBooks•Sep 2, 2010•0 citations
Summary form only given. In high-precision atomic experiments such as atomic interferometry, the accuracy is ultimately limited by the so-called quantum projection noise, due to the fact that the atoms are not in an eigenstate of the measured quantity. In an ensemble of N independent atoms, fluctuations proportional to N/sup -1/2/ result from this effect. A few years ago, it was shown that using squeezed atomic states would allow to reduce these fluctuations, in the same way as squeezed states of light allow to obtain noise reduction in measurements of the electromagnetic field.
Ultimate quantum fluctuations which limit the fundamental precision in metrology can be only reduced by entanglement of particles. In particular, squeezing of the fluctuations called the spin projection noise by means of generation of entanglement in an ensemble of atoms can improve the precision of spectroscopy and of atomic clocks. A powerful tool for generation of multiparticle entanglement is a quantum nondemolition measurement (QND). We will describe the fundamentals of QND measurement of atomic collective state with light and present a recent experiment [1] where this method has been used to reduce the projection noise on the clock transition in an ensemble of 105 cold and trapped Cesium atoms. Another method for generation of spin squeezing via electron-nucleus entanglement applicable only for atoms with angular momentum higher than ½ will be also discussed [2].
Quantum Sensors, like atom interferometers (AI), can be employed for high-precision measurements of inertial forces, including their application as gravimeters, gradiometers, accelerometers, and gyroscopes. Their measurement principle relies on ultracold atoms that are prepared in quantum-mechanical superposition states in external degrees of freedom. These states can be prepared by a momentum transfer of a Raman laser. Then the superposition state senses the effect of an inertial force, which induce a corresponding relative phase. The phase is read out by a final coupling which converts the interferometric phase into a atom number difference between the two states. The difference provides an estimate of the interferometric phase and the corresponding quantity of interest. The quantum mechanical noise of the atomic ensemble cause a fundamental uncertainty of this estimation, which I analyze for generic AIs. For small atomic densities, the quantum phase noise of the ensemble limits the interferometric sensitivity. For large densities, quantum number fluctuations generate density fluctuations, which generates phase noise. I show that these two competing effects result in an optimal atom number with a maximal interferometer resolution. Squeezed atomic samples allow for a reduction of the quantum noise of one quantity at the expense of an increased noise along of a conjugate quantity. Phase and number are such quantities which obey to a variant of Heisenberg’s uncertainty principle. Neither phase nor number squeezing can improve the maximal interferometer resolution. As one main result of this thesis, I show how an optimal squeezing in between number and phase squeezing, allows for a fundamental improvement. I evaluate possible experimental paths to implement the proposed protocol. Concepts for a squeezing-enhanced operation of external-degree AIs have not yet been demonstrated. I propose and implement an atomic gravimeter, which is designed to accept spin-squeezed atomic states as input states. The interferometer is designed such that the interferometer couplings are performed in spin space, while the phase accumulation is performed in momentum states. For this interferometer, the squeezed input can be directly obtained from spin dynamics in spinor Bose-Einstein condensates. The main noise contributions in the experiment are analyzed, which results in a factor of 84 above the relevant quantum limit, preventing a squeezing enhancement so far. I outline a suppression of the main noise source, uncontrolled AC Stark shift on the squeezed mode and propose future important applications, including test of spontaneous collapse theories and an improvement of large-scale, high-precision gradiometers.
Atom interferometer measurements are affected by the amount of quantum noise from the laser used to detect atoms. To improve the quantum limited sensitivity of interferometers, there needs to be a way to reduce the amount of quantum noise. Light is composed of two quadratures, where the product of the noise in each quadrature cannot be below a minimum threshold set by the Heisenberg Uncertainty Principle. However, the noise in one quadrature can be reduced at the expense of the other. This form of light is referred to as “squeezed light.” Squeezed light can be produced using four-wave mixing (FWM). Electromagnetically induced transparency (EIT) is an interference phenomenon that occurs when a three-level atom is driven by a coherent field that makes a non-linear medium transparent to the probing field and holds a great deal of similarities to FWM. This thesis developed a theoretical framework that describes the measurement of atomic states and associated noise when quantum light is used to drive the atom and lays the groundwork to produce squeezed light through developing an experiment to produce EIT, as well as discussing the similarities between EIT and FWM to create and further study FWM for improved atom interferometry.
We provide a framework for understanding recent experiments on squeezing of a collective atomic pseudo-spin, induced by a homodyne measurement on off-resonant probe light interrogating the atoms. The detection of light decimates the atomic state distribution and we discuss the conditions under which the resulting reduced quantum fluctuations are metrologically relevant. In particular, we consider a dual probe scheme which benefits from a cancelation of classical common mode noise sources such that quantum fluctuations from light and atoms are the main contributions to the detected signal.
Spin-squeezed state is a many-body entangled state of great interest for precision measurements. Although the absolute sensitivity at the standard quantum limit is better for a larger atom number, the greater dominance of classical noises over atom projection noise makes it harder to achieve spin squeezing. Here, we show both theoretically and experimentally that adiabatic pulse control of the pump field in state preparation is indispensable to sufficient noise suppression, which is the prerequisite for spin squeezing. This technique is generally applicable to spin-squeezing experiments involving a large ensemble and is thus of significance for quantum metrology applications.
We showed in Section 5.2 of the present chapter that according to quantum theory the value of the electric field of an electromagnetic wave could not be predicted to arbitrarily high precision, this being a consequence of the uncertainty relation satisfied by the two quadrature components of the field (Equation 5.32), which imposed a finite limit on the product of their variances. This limit is more than an abstract theoretical limit; it is often the overriding factor determining the resolution of high-precision optical measurements. In such situations measurements by photodetectors on the field exhibit uncontrollable fluctuations of quantum origin known as quantum noise . Fortunately, as we shall show in this complement, it is possible to overcome this by using non-classical states of the radiation field, namely the squeezed states , provided measurements are made of a single one of a pair of conjugate field variables. A field mode prepared in such a state exhibits reduced quantum noise in one of the variables at the expense of increased noise in the other, so that the uncertainty relation involving their variances is still satisfied. The potential of such states for increasing the obtainable precision of optical measurements is self-evident. However, the practical realization of the potential benefits requires delicate experimental techniques that we describe only briefly here.