Category Tsinghua National Laboratory for Information Science and Technology

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Mechanical PT symmetry in coupled optomechanical systems

Mar 3, ’14 8:14 AM

Xun-Wei Xu, Yu-xi Liu, Chang-Pu Sun, Yong Li

We propose to observe mechanical PT symmetry in the coupled optomechanical systems. In order to provide gain to one mechanical resonator and equivalent amount of damp to another, we drive the two optical cavities with a blue and a red detuned laser fields respectively. After adiabatically eliminating the freedom of the cavity modes, we develop a formalism for describing mechanical PT-symmetric system. Moreover, we discuss the experimental feasibility of our scheme and show that the observation of mechanical PT-symmetric transition in the coupled optomechanical systems is within the reach of resent experiments.

http://arxiv.org/abs/1402.7222

Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Optics (physics.optics)

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Reply on Comments on “Observation of a Fast Evolution in a Parity-time-symmetric System”(ArXiv:1106.1550)

Jun 10, ’11 11:03 AM

Chao Zheng, Liang Hao, Gui Lu Long

Masillo [1] commented on our manuscript [2] “Observation of a Fast Evolution in a Parity-time-symmetric System”, pointing out a contradiction of our work with Ref.[3]. In this reply, we pointed out there is no disagreement between Masillo’s comment and our work in Ref. [2]. The efficiency cost pointed out in Ref.\cite{masillo} exists, namely to obtain the PT-symmetric hamiltonian evolution, one has to make a measurement on the auxiliary qubit and the auxiliary qubit is at state \(\left|0\right \rangle\) only probabilistically. This is reflected in the amplitude of the spectrum in the NMR quantum simulation. As a result, we made a small modification in a new version of the Ref. [2], and Fig. 2 of Ref.[2] has been replaced by spectra of two different \(\alpha\)’s in order to illustrate this fact.

http://arxiv.org/abs/1106.1848
Quantum Physics (quant-ph)

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Observation of Fast Evolution in Parity-Time-Symmetric System

Jun 2, ’11 12:16 AM

Chao Zheng, Liang Hao, Gui Lu Long

To find and realize the optimal evolution between two states is significant both in theory and application. In quantum mechanics, the minimal evolution is bounded by the gap between the largest and smallest eigenvalue of the Hamiltonian. In the parity-time-symmetric(PT-symmetric) Hamiltonian theory, it was predicted that the optimized evolution time can be reduced drastically comparing to the bound in the Hermitian case, and can become even zero. In this Letter, we report the experimental observation of the fast evolution of a PT-symmetric Hamiltonian in an nuclear magnetic resonance (NMR) quantum system. The experimental results demonstrate that the PT-symmetric Hamiltonian can indeed evolve much faster than that in a quantum system, and time it takes can be arbitrary close to zero.

http://arxiv.org/abs/1105.6157
Quantum Physics (quant-ph)

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