We study the time degradation of quantum information stored in a quantum memory device under a dissipative environment in a parameter range which is experimentally relevant. The quantum memory under consideration comprises of an optomechanical system with additional Kerr non-linearity in the optical mode and an anharmonic mechanical oscillator with quadratic non-linearity. Time degradation is monitored, both in terms of loss of coherence which is analyzed with the help of Wigner functions, as well as in terms of loss of amplitude of the original state studied as a function of time. While our time trajectories explore the degree to which the stored information degrades depending upon the variation in values of various parameters involved, we suggest a set of parameters for which the original information can be retrieved without degradation. We come across a highly attention seeking situation where the role played by the non-linearity is insignificant and the system behaves as if the information is stored in a linear medium. For this case, the information retrieval is independent of the coherence revival time and can be retrieved at any instant during the time evolution.We study the time degradation of quantum information stored in a quantum memory device under a dissipative environment in a parameter range which is experimentally relevant. The quantum memory under consideration comprises of an optomechanical system with additional Kerr non-linearity in the optical mode and an anharmonic mechanical oscillator with quadratic non-linearity. Time degradation is monitored, both in terms of loss of coherence which is analyzed with the help of Wigner functions, as well as in terms of loss of amplitude of the original state studied as a function of time. While our time trajectories explore the degree to which the stored information degrades depending upon the variation in values of various parameters involved, we suggest a set of parameters for which the original information can be retrieved without degradation. We come across a highly attention seeking situation where the role played by the non-linearity is insignificant and the system behaves as if the information is stored in a linear medium. For this case, the information retrieval is independent of the coherence revival time and can be retrieved at any instant during the time evolution.

arXiv:2201.06909Jan 18, 20220 citations

Creation, storage, and retrieval of an optomechanical cat state

Run Yan Teh, Simon Kiesewetter, P. D. Drummond +1 more

We analyze a method for the creation, storage, and retrieval of optomechanical Schr\"odinger cat states, in which there is a quantum superposition of two distinct macroscopic states of a mechanical oscillator. In the quantum memory protocol, an optical cat state is first prepared in an optical cavity, then transferred to the mechanical mode, where it is stored and later retrieved using control fields. We carry out numerical simulations for the quantum memory protocol for optomechanical cat states using the positive-P phase space representation. This has a compact, positive representation for a cat state, thus allowing a probabilistic simulation of this highly nonclassical quantum system. It is essential to use importance sampling to carry out the simulation effectively. To verify the effectiveness of the cat-state quantum memory, we consider several cat-state signatures and show how they can be computed. We also investigate the effects of decoherence on a cat state by solving the standard master equation for a simplified model analytically, allowing us to compare with the numerical results. Focusing on the negativity of the Wigner function as a signature of the cat state, we evaluate analytically an upper bound on the time taken for the negativity to vanish, for a given temperature of the environment of the mechanical oscillator. We show consistency with the numerical methods. These provide exact solutions, allowing a full treatment of decoherence in an experiment that involves creating, storing, and retrieving mechanical cat states using temporally mode-matched input and output pulses. Our analysis treats the internal optical and mechanical modes of an optomechanical oscillator, and the complete set of input and output field modes which become entangled with the internal modes. The model includes decoherence due to thermal effects in the mechanical reservoirs, as well as optical and mechanical losses.We analyze a method for the creation, storage, and retrieval of optomechanical Schr\"odinger cat states, in which there is a quantum superposition of two distinct macroscopic states of a mechanical oscillator. In the quantum memory protocol, an optical cat state is first prepared in an optical cavity, then transferred to the mechanical mode, where it is stored and later retrieved using control fields. We carry out numerical simulations for the quantum memory protocol for optomechanical cat states using the positive-P phase space representation. This has a compact, positive representation for a cat state, thus allowing a probabilistic simulation of this highly nonclassical quantum system. It is essential to use importance sampling to carry out the simulation effectively. To verify the effectiveness of the cat-state quantum memory, we consider several cat-state signatures and show how they can be computed. We also investigate the effects of decoherence on a cat state by solving the standard master equation for a simplified model analytically, allowing us to compare with the numerical results. Focusing on the negativity of the Wigner function as a signature of the cat state, we evaluate analytically an upper bound on the time taken for the negativity to vanish, for a given temperature of the environment of the mechanical oscillator. We show consistency with the numerical methods. These provide exact solutions, allowing a full treatment of decoherence in an experiment that involves creating, storing, and retrieving mechanical cat states using temporally mode-matched input and output pulses. Our analysis treats the internal optical and mechanical modes of an optomechanical oscillator, and the complete set of input and output field modes which become entangled with the internal modes. The model includes decoherence due to thermal effects in the mechanical reservoirs, as well as optical and mechanical losses.

arXiv:1809.00608Physical Review ADec 7, 201832 citations

Revisiting quantum memory efficiency using quantum coherence functions

Hassana Kokab, Farhan Saif

Abstract We show that a two-sided hybrid optomechanical (OM) system is capable of storing and retrieving information with controllable memory efficiency. The control of OM coupling, primarily arising from optomechanically induced transparency, plays a central role in our approach. By introducing an effective optical depth (OD) associated with the OM interaction, we analyze its impact on quantum memory efficiency and contrast it with the limitations imposed by the OD in Jaynes–Cummings-type coupling. Our study is based on the evaluation of first-order and second-order correlation functions, providing insight into coherence and quantum statistics. All parameters considered are within experimentally feasible regimes, highlighting the practical potential of the proposed quantum memory architecture.Abstract We show that a two-sided hybrid optomechanical (OM) system is capable of storing and retrieving information with controllable memory efficiency. The control of OM coupling, primarily arising from optomechanically induced transparency, plays a central role in our approach. By introducing an effective optical depth (OD) associated with the OM interaction, we analyze its impact on quantum memory efficiency and contrast it with the limitations imposed by the OD in Jaynes–Cummings-type coupling. Our study is based on the evaluation of first-order and second-order correlation functions, providing insight into coherence and quantum statistics. All parameters considered are within experimentally feasible regimes, highlighting the practical potential of the proposed quantum memory architecture.

Journal of Physics B Atomic Molecular and Optical PhysicsNov 13, 20251 citation

A Long-lived and Efficient Optomechanical Memory for Light

M. Kristensen, Kralj, Nenad, Eric Langman +1 more

We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultra-low dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime $T_1 \approx 23\,\mathrm{ms}$ and a retrieval efficiency $η\approx 40\%$ for classical coherent pulses. We anticipate storage of quantum light to be possible at moderate cryogenic conditions ( $T\approx 10\,\mathrm{K}$ ). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultra-low dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime $T_1 \approx 23\,\mathrm{ms}$ and a retrieval efficiency $η\approx 40\%$ for classical coherent pulses. We anticipate storage of quantum light to be possible at moderate cryogenic conditions ($T\approx 10\,\mathrm{K}$). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.

arXiv:2308.05206Aug 9, 20230 citations

Long-lived and Efficient Optomechanical Memory for Light

M. Kristensen, Nenad Kralj, Eric Langman +1 more

We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultralow dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime ${T}_{1}\ensuremath{\approx}23\text{ }\text{ }\mathrm{ms}$ and a retrieval efficiency $\ensuremath{\eta}\ensuremath{\approx}40%$ for classical coherent pulses. We anticipate the storage of quantum light to be possible at moderate cryogenic conditions ($T\ensuremath{\approx}10\text{ }\text{ }\mathrm{K}$). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultralow dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime ${T}_{1}\ensuremath{\approx}23\text{ }\text{ }\mathrm{ms}$ and a retrieval efficiency $\ensuremath{\eta}\ensuremath{\approx}40%$ for classical coherent pulses. We anticipate the storage of quantum light to be possible at moderate cryogenic conditions ($T\ensuremath{\approx}10\text{ }\text{ }\mathrm{K}$). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.

Physical Review LettersMar 5, 202430 citations

Joint quantum estimation of loss and nonlinearity in driven-dissipative Kerr resonators

Muhammad Asjad, Berihu Teklu, Matteo G. A. Paris

We address multiparameter quantum estimation for coherently driven nonlinear Kerr resonators in the presence of loss. In particular, we consider the realistic situation in which the parameters of interest are the loss rate and the nonlinear coupling, whereas the amplitude of the coherent driving is known and externally tunable. Our results show that this driven-dissipative model is asymptotically classical, i.e., the Uhlmann curvature vanishes, and the two parameters may be jointly estimated without any additional noise of quantum origin. We also find that the ultimate bound to precision, as quantified by the quantum Fisher information (QFI), increases with the interaction time and the driving amplitude for both parameters. Finally, we investigate the performance of quadrature detection, and show that for both parameters the Fisher information oscillates in time, repeatedly approaching the corresponding QFI.We address multiparameter quantum estimation for coherently driven nonlinear Kerr resonators in the presence of loss. In particular, we consider the realistic situation in which the parameters of interest are the loss rate and the nonlinear coupling, whereas the amplitude of the coherent driving is known and externally tunable. Our results show that this driven-dissipative model is asymptotically classical, i.e., the Uhlmann curvature vanishes, and the two parameters may be jointly estimated without any additional noise of quantum origin. We also find that the ultimate bound to precision, as quantified by the quantum Fisher information (QFI), increases with the interaction time and the driving amplitude for both parameters. Finally, we investigate the performance of quadrature detection, and show that for both parameters the Fisher information oscillates in time, repeatedly approaching the corresponding QFI.

arXiv:2212.05117Physical Review ResearchMar 17, 202339 citations

T_1 \approx 23\,\mathrm{ms}

and a retrieval efficiency

η\approx 40\%

for classical coherent pulses. We anticipate storage of quantum light to be possible at moderate cryogenic conditions (

T\approx 10\,\mathrm{K}

). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.