Optimal Protection of Quantum Coherence in Noisy Environment

2016 ◽  
Vol 56 (2) ◽  
pp. 503-513 ◽  
Author(s):  
Zhiming Huang ◽  
Haozhen Situ
2020 ◽  
Vol 34 (12) ◽  
pp. 2050124
Author(s):  
Zhiming Huang ◽  
Zhimin He

Quantum state sharing plays an important role in both transmitting and protecting a quantum secret information. However, in a realistic situation, quantum communication protocol is inevitably affected by the decoherence and noise induced by the interaction between quantum system and environment, which often destroys quantum resource, such as degrading entangled state that is often used as the key resource of quantum communication. In this paper, we intend to investigate the influence of amplitude damping (AD) decoherence on multi-party qutrit-state sharing (MQSS) scheme. We firstly construct the noisy model of MQSS, and then analyze the effect of decoherence on the MQSS. In addition, the relation of variations between MQSS performance and quantum coherence is illustrated. Furthermore, we propose a partial measurement to enhance the performance of the MQSS under noisy environment.


2020 ◽  
Vol 34 (07) ◽  
pp. 2050051
Author(s):  
Zhiming Huang

Inevitable interaction between quantum system and environment will induce decoherence which would destroy the quantum coherence (QC) of quantum system. In this paper, we examine the QC behaviors for a single qubit locally coupled to the zero-temperature multiple bosonic reservoirs. Comparing the Markovian and non-Markovian QC behaviors, it is demonstrated that QC decays as decoherent time goes by, and non-Markovian QC exhibits obvious oscillating behaviors. The oscillatory frequency and amplitude increase with growing coupling strength and number of reservoirs. In addition, in non-Markovian regime, QC vanishes at some discrete critical time points. Finally, we reveal an effective method to suppress decoherence with filtering operation.


Author(s):  
Eun-Jung Lim ◽  
Kyu-Yup Lee ◽  
Yee-Hyuk Kim ◽  
Chang-Min Sin ◽  
Sung-Jae Youn ◽  
...  

1998 ◽  
Vol 36 (1) ◽  
pp. 66-69 ◽  
Author(s):  
Keiichi MIKI ◽  
Kouki KAWAMORITA ◽  
Yutaka ARAGA ◽  
Toshimitsu MUSHA ◽  
Ayako SUDO

Author(s):  
Ana Maria Ariciu ◽  
David H. Woen ◽  
Daniel N. Huh ◽  
Lydia Nodaraki ◽  
Andreas Kostopoulos ◽  
...  

Using electron spins within molecules for quantum information processing (QIP) was first proposed by Leuenberger and Loss (1), who showed how the Grover algorithm could be mapped onto a Mn12 cage (2). Since then several groups have examined two-level (S = ½) molecular spin systems as possible qubits (3-12). There has also been a report of the implementation of the Grover algorithm in a four-level molecular qudit (13). A major challenge is to protect the spin qubit from noise that causes loss of phase information; strategies to minimize the impact of noise on qubits can be categorized as corrective, reductive, or protective. Corrective approaches allow noise and correct for its impact on the qubit using advanced microwave pulse sequences (3). Reductive approaches reduce the noise by minimising the number of nearby nuclear spins (7-11), and increasing the rigidity of molecules to minimise the effect of vibrations (which can cause a fluctuating magnetic field via spin-orbit coupling) (9,11); this is essentially engineering the ligand shell surrounding the electron spin. A protective approach would seek to make the qubit less sensitive to noise: an example of the protective approach is the use of clock transitions to render spin states immune to magnetic fields at first order (12). Here we present a further protective method that would complement reductive and corrective approaches to enhancing quantum coherence in molecular qubits. The target is a molecular spin qubit with an effective 2S ground state: we achieve this with a family of divalent rare-earth molecules that have negligible magnetic anisotropy such that the isotropic nature of the electron spin renders the qubit markedly less sensitive to magnetic noise, allowing coherent spin manipulations even at room temperature. If combined with the other strategies, we believe this could lead to molecular qubits with substantial advantages over competing qubit proposals.<br>


2018 ◽  
Vol 1 (March 2018) ◽  
Author(s):  
S.A Okanlawon ◽  
O.O Odunjo ◽  
S.A Olaniyan

This study examined Residents’ evaluation of turning transport infrastructure (road) to spaces for holding social ceremonies in the indigenous residential zone of Ogbomoso, Oyo State, Nigeria. Upon stratifying the city into the three identifiable zones, the core, otherwise known as the indigenous residential zone was isolated for study. Of the twenty (20) political wards in the two local government areas of the town, fifteen (15) wards that were located in the indigenous zone constituted the study area. Respondents were selected along one out of every three (33.3%) of the Trunk — C (local) roads being the one mostly used for the purpose in the study area. The respondents were the residents, commercial motorists, commercial motorcyclists, and celebrants. Six hundred and forty-two (642) copies of questionnaire were administered and harvested on the spot. The Mean Analysis generated from the respondents’ rating of twelve perceived hazards listed in the questionnaire were then used to determine respondents’ most highly rated perceived consequences of the practice. These were noisy environment, Blockage of drainage by waste, and Endangering the life of the sick on the way to hospital; the most highly rated reasons why the practice came into being; and level of acceptability of the practice which was found to be very unacceptable in the study area. Policy makers should therefore focus their attention on strict enforcement of the law prohibiting the practice in order to ensure more cordial relationship among the citizenry, seeing citizens’ unacceptability of the practice in the study area.


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