Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath beyond the rotating-wave approximation

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	Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath beyond the rotating-wave approximation
	Cao,XF ; You,JQ ; Nori,F ; Kofman,AG ; Zheng,H ; Cao XF(曹秀凤)
刊名	http://dx.doi.org/10.1103/PhysRevA.82.022119
	2010-08-30
关键词	DECOHERENCE STATE
英文摘要	Laboratory of Physical Sciences; National Security Agency; Army Research Office; National Science Foundation [0726909]; JSPS-RFBR [09-02-92114]; MEXT; Funding Program for Innovative R&D on ST (FIRST); National Natural Science Foundation of China [10904126; We use a non-Markovian approach to study the decoherence dynamics of a qubit in either a low- or high-frequency bath modeling the qubit environment. This is done for two separate cases: either with measurements or without them. This approach is based on a unitary transformation and does not require the rotating-wave approximation. In the case without measurement, we show that, for low- frequency noise, the bath shifts the qubit energy toward higher energies (blue shift), while the ordinary high-frequency cutoff Ohmic bath shifts the qubit energy toward lower energies (red shift). In order to preserve the coherence of the qubit, we also investigate the dynamics of the qubit subject to measurements (quantum Zeno regime) in two cases: low- and high-frequency baths. For very frequent projective measurements, the low- frequency bath gives rise to the quantum anti-Zeno effect on the qubit. The quantum Zeno effect only occurs in the high-frequency-cutoff Ohmic bath, after counterrotating terms are considered. In the condition that the decay rate due to the two kinds of baths are equal under the Wigner-Weisskopf approximation, we find that without the approximation, for a high-frequency environment, the decay rate should be faster (without measurements) or slower (with frequent measurements, in the Zeno regime), compared to the low- frequency bath case. The experimental implementation of our results here could distinguish the type of bath (either a low- or high-frequency one) and protect the coherence of the qubit by modulating the dominant frequency of its environment.
语种	英语
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/69290]
专题	物理技术－已发表论文
推荐引用方式 GB/T 7714	Cao,XF,You,JQ,Nori,F,et al. Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath beyond the rotating-wave approximation[J]. http://dx.doi.org/10.1103/PhysRevA.82.022119,2010.
APA	Cao,XF,You,JQ,Nori,F,Kofman,AG,Zheng,H,&曹秀凤.(2010).Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath beyond the rotating-wave approximation.http://dx.doi.org/10.1103/PhysRevA.82.022119.
MLA	Cao,XF,et al."Dynamics and quantum Zeno effect for a qubit in either a low- or high-frequency bath beyond the rotating-wave approximation".http://dx.doi.org/10.1103/PhysRevA.82.022119 (2010).