We analyze the reading and initialization of a topological qubit encoded by Majorana fermions in one-dimensional semiconducting nanowires, weakly coupled to a single level quantum dot(QD). It is shown that when the Ma...We analyze the reading and initialization of a topological qubit encoded by Majorana fermions in one-dimensional semiconducting nanowires, weakly coupled to a single level quantum dot(QD). It is shown that when the Majorana fermions are fused by tuning gate voltage, the topological qubit can be read out directly through the occupation of the QD in an energy window. The initialization of the qubit can also be realized via adjusting the gate voltage on the QD, with the total fermion parity conserved. As a result, both reading and initialization processes can be achieved in an all-electrical way.展开更多
We propose a scheme to achieve a kind of nontrivial two-qubit operation using controllable electrons in double-dot molecules coupled to a transmission line resonator.The implemented operation is geometrical in nature ...We propose a scheme to achieve a kind of nontrivial two-qubit operation using controllable electrons in double-dot molecules coupled to a transmission line resonator.The implemented operation is geometrical in nature and insensitive to the state of the transmission line resonator.In particular,we are able to avoid conventional dispersive coupling so that a high speed gate operation can be achieved,which is important in view of decoherence.Meanwhile,we are able to further generalize the operation to an arbitrary phase case by dynamic decoupling with two sequences.展开更多
We propose a scheme to achieve a kind of nontrivial multipartite pair-wise controlled phase operation in a cavity QED setup. The operation implemented is of geometrical nature and is not sensitive to the thermal state...We propose a scheme to achieve a kind of nontrivial multipartite pair-wise controlled phase operation in a cavity QED setup. The operation implemented is of geometrical nature and is not sensitive to the thermal state of the cavity. In particular, we have managed to avoid the conventional dispersive coupling so that high speed gate operation is achieved which is very important in view of decoherence. We show that this multipartite pair-wise controlled phase operation makes the generation of two-dimensional cluster states very efficient.展开更多
Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase...Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase transition.We design the spinboson model by using a superconducting phase qubit coupled to a semi-infinite transmission line,which is regarded as a bosonic reservoir with a continuum spectrum.By tuning the bias current or the coupling capacitance,the quantum KT transition can be directly detected through tomography measurement on the states of the phase qubit.We also estimate the experimental parameters using the numerical renormalization group method.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CB922100,2011CBA00205,and 2013CB921804)the General Research Fund(GRF)of the Research Grants Council(RGC)of Hong Kong,China(Grant Nos.HKU7058/11P and HKU7045/13P)+6 种基金the Collaborative Research Fund(CRF)of the Research Grants Council(RGC)of Hong Kong,China(Grant No.HKU-8/11G)the University Research Committee(URC)Fund of the Hong Kong University(HKU),Chinathe National Natural Science Foundation of China(Grant Nos.11074111,11023002,and 11004065)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Program for New Century Excellent Talents in University of Ministry of Education of Chinathe Program for Changjiang Scholars and Innovative Research Team in University,Chinathe Fundamental Research Funds for the Central Universities of Ministry of Education of China
文摘We analyze the reading and initialization of a topological qubit encoded by Majorana fermions in one-dimensional semiconducting nanowires, weakly coupled to a single level quantum dot(QD). It is shown that when the Majorana fermions are fused by tuning gate voltage, the topological qubit can be read out directly through the occupation of the QD in an energy window. The initialization of the qubit can also be realized via adjusting the gate voltage on the QD, with the total fermion parity conserved. As a result, both reading and initialization processes can be achieved in an all-electrical way.
基金Supported by the National Natural Science Foundation of China under Grant No 11004065the Natural Science Foundation of Guangdong Province(No 10451063101006312)+1 种基金the Key Project of the Education Department of Anhui Province(No KJ2010A323)the Startup Foundation of SCNU(No S53005).
文摘We propose a scheme to achieve a kind of nontrivial two-qubit operation using controllable electrons in double-dot molecules coupled to a transmission line resonator.The implemented operation is geometrical in nature and insensitive to the state of the transmission line resonator.In particular,we are able to avoid conventional dispersive coupling so that a high speed gate operation can be achieved,which is important in view of decoherence.Meanwhile,we are able to further generalize the operation to an arbitrary phase case by dynamic decoupling with two sequences.
基金Project supported by the National Fundamental Research Program of China (Grant No. 2013CB921804)the National Natural Science Foundation of China(Grant No. 11004065)+1 种基金the Natural Science Foundation of Guangdong Province of China (Grant Nos. 10451063101006312 and S2011040000403)the Funds of the Education Department of Anhui Province of China (Grant Nos. KJ2010A323, 2010SQRL187, and KJ2012B075)
文摘We propose a scheme to achieve a kind of nontrivial multipartite pair-wise controlled phase operation in a cavity QED setup. The operation implemented is of geometrical nature and is not sensitive to the thermal state of the cavity. In particular, we have managed to avoid the conventional dispersive coupling so that high speed gate operation is achieved which is very important in view of decoherence. We show that this multipartite pair-wise controlled phase operation makes the generation of two-dimensional cluster states very efficient.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11004065,11104057 and 11125417)the Natural Science Foundation of Guangdong Province (Grant No.10451063101006312)+1 种基金the State Key Program for Basic Research of China(Grant No. 2011CB922104)the GRF and CRF of the RGC of Hong Kong
文摘Based on the rapid experimental developments of circuit QED,we propose a feasible scheme to simulate the spin-boson model with superconducting circuits,which can be used to detect quantum Kosterlitz-Thouless(KT) phase transition.We design the spinboson model by using a superconducting phase qubit coupled to a semi-infinite transmission line,which is regarded as a bosonic reservoir with a continuum spectrum.By tuning the bias current or the coupling capacitance,the quantum KT transition can be directly detected through tomography measurement on the states of the phase qubit.We also estimate the experimental parameters using the numerical renormalization group method.