Spin squeezing via one- and two-axis twisting induced by a single off-resonance stimulated Raman scattering in a cavity

Abstract

Squeezed spin states have important applications in quantum metrology and sensing. It has been shown by Sørensen and Mølmer [Phys. Rev. A 66, 022314(2002)] that an effective one-axis-twisting interaction can be realized in a cavity setup via a double off-resonance stimulated Raman scattering, resulting in a noise reduction scaling ∝ 1/N 2/3 with N being the atom number. Here, we show that, by making an appropriate change of the initial input spin state, it is possible to produce a oneaxis-twisting spin squeezing via a single off-resonance stimulated Raman scattering, which thus can greatly simplify the realistic implementation. We also show that the one-axis-twisting interaction can be transformed into a more efficient two-axis-twisting interaction by rotating the collective spin while coupling to the cavity, yielding a Heisenberg limited noise reduction ∝ 1/N . Considering the noise effects due to atomic decoherence and cavity decay, we find that substantial squeezing is still attainable with current laboratory techniques.

Spin two-axis-twisting via coherent population trapping based cavity QED

“…So far many efforts have been devoted to the generation of spin squeezing in atomic ensembles via atom-photon interactions, i.e. cavity quantum electrodynamics (QED) [33][34][35][36][37][38][39][40][41][42][43][44][45].…”

“…Since the atoms are hardly excited, spontaneous emission is almost avoided. Some cavity QED schemes have been proposed for the unitary one-and two-axis twisting [33][34][35][36][37][38][39][40][41][42][43][44][45]. Among them, Sørensen and Mølmer proposed to realize an effective one-axis twisting Hamiltonian like H eff = hβJ 2 z via double far-off-resonance stimulated Raman scattering [38] in Λ configuration.…”

“…Among them, Sørensen and Mølmer proposed to realize an effective one-axis twisting Hamiltonian like H eff = hβJ 2 z via double far-off-resonance stimulated Raman scattering [38] in Λ configuration. This method was extended to generate an effective two-axis twisting Hamiltonian in a similar cavity setup [39,40]. With the aid of phase-lock atom-photon coupling, Zhou et al [41] presented the two-axis countertwisting spin-squeezing Hamiltonian like H eff = hβ(J 2 z − J 2 y ) inside an optical cavity.…”

Strong spin squeezing induced by weak squeezing of light inside a cavity

“…This is partially attributed to the need for multiple classical and cavity-photon drivings applied to atoms. For example, various approaches for spin squeezing in cavities rely on a double off-resonant Raman transition (i.e., the double-Λ transition) [25,31,[40][41][42][43][44][45]. It is generally difficult to realize such a transition for each atom in ensembles for spin squeezing.…”

Strong Spin Squeezing Induced by Weak Squeezing of Light inside a Cavity

“…This is partially attributed to the need for multiple classical and cavity-photon drivings applied to individual atoms. For example, various approaches for spin squeezing in cavities rely on a double off-resonant Raman transition (i.e., the double-Λ transition) [23,29,[37][38][39][40][41][42]. It is generally difficult to realize such a transition for each atom in ensembles for spin squeezing.…”