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Yoav Shimshi

Publications and source records attributed to Yoav Shimshi.

2 recordsLinked to original sources

Critical quantum metrology beyond adiabaticity in collectively pumped superradiance

Critical metrology relies on the high sensitivity of systems to parameter changes near a phase transition to extract information with high precision. Such methods usually require working under adiabatic conditions, which implies long preparation times due to critical slowing down. Here instead we demonstrate how favorable sensitivity can be maintained for preparation rates exceeding the adiabatic limit by exploiting knowledge of the non-equilibrium dynamics of the system. Our work focuses on a model of collective dissipation (superradiance) balanced by collective pumping, analyzing the sensitivity around a first order dissipative phase transition. We devise a sensing protocol based on characterizing the hysteresis formed beyond adiabatic conditions, finding the sensing uncertainty $r^{\alpha}/N$ , exhibiting a favorable Heisenberg-like scaling with the particle number $N$ and only a weak power-law dependence $\alpha \approx 0.17$ on the preparation rate $r$. We discuss the implementation of the model and potential applications to metrology within cavity QED setups.

quant-ph

Heisenberg-Langevin approach to driven superradiance

We present an analytical approach for the study of driven Dicke superradiance based on a Heisenberg-Langevin formulation. We calculate the steady-state fluctuations of both the atomic-spin and the light-field operators. While the atoms become entangled below a critical drive, exhibiting spin squeezing, we show that the radiated light is in a classical-like coherent state whose amplitude and spectrum are identical to those of the incident driving field. Therefore, the nonlinear atomic system scatters light as a linear classical scatterer. Our results are consistent with the recent theory of coherently radiating spin states. The presented Heisenberg-Langevin approach should be simple to generalize for treating superradiance beyond the permutation-symmetric Dicke model.

quant-ph