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Dissipative Quantum Computing with majorana fermions

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Journal of Applied Mathematics and Physics 2016年第2期4卷 227-232页

作者： Henning Soller Institut für Theoretische Physik Ruprecht-Karls-Universit&#252 t Heidelberg Heidelberg Germany

We describe a scheme for universal quantum computation with majorana fermions. We investigate two possible dissipative couplings of majorana fermions to external systems, including metallic leads and local phonons. While the dissipation when coupling to metallic leads to uninteresting states for the majorana fermions, we show that coupling the majorana fermions to local phonons allows to generate arbitrary dissipations and therefore universal quantum operations on a single QuBit that can be enhanced by additional two-QuBit operations.

关键词： Dissipative Quantum Computing Phonon Interaction majorana fermions Universal Quantum Computation

All-optical scheme for detecting the possible majorana signature based on QD and nanomechanical resonator systems

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Science China(Physics,Mechanics & Astronomy) 2015年第5期58卷 2-15页

作者： CHEN HuaJun ZHU KaDi Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education) Department of Physics and Astronomy Shanghai Jiao Tong University

majorana fermions(MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, because of their importance in fundamental physics and potential applications in topological quantum computation based on solid-state devices. Motivated by recent experimental progress towards the detection and manipulation of MFs in hybrid semiconductor/superconductor heterostructures, in this review, we present a novel proposal to probe MFs in all-optical domain. We introduce a single quantum dot(QD), a hybrid quantum dot-nanomechanical resonators(QD-NR) system, and a carbon nanotube(CNT) resonator implanted in a single electron spin system with optical pump-probe technology to detect MFs, respectively. With this scheme, a possible majorana signature is investigated via the probe absorption spectrum and nonlinear optical Kerr effect, and the coupling strength between MFs and the QD or the single electron spin is also determined. In the hybrid QD-NR system, vibration of the NR will enhance the nonlinear optical effect, which makes the MFs more sensitive for detection. In the CNT resonator with a single electron, the single electron spin can be considered as a sensitive probe, and the CNT resonator behaved as a phonon cavity is robust for detecting of MFs. This optical scheme will provide another method for the detection MFs and will open the door for new applications ranging from robust manipulation of MFs to quantum information processing based on MFs.

关键词： majorana fermions QD nanomechanical resonator carbon nanotube resonator optical pump-probe technology

Hinge majorana flat band in type-Ⅱ Dirac semimetals

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 127-132页

作者： Yue Xie Xianxin Wu Zhong Fang Zhijun Wang Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing100190China

Type-Ⅱ Dirac semimetals exhibit a unique Fermi surface topology,which allows them to host novel topological superconductivity(TSC).We reveal a novel inter-orbital superconducting state,corresponding to the B_(1u) and B_(2u) pairings under the D_(4h) point ***,we find that both first-and second-order TSC coexist in this novel *** is induced by a dominant inter-orbital attraction and possesses surface helical majorana cones and hinge majorana flat bands,spanning the entire z-directed hinge Brillouin *** investigation uncovers that these higher-order hinge modes are robust against the C_(4z) symmetry-breaking perturbation.

关键词： topological superconductivity majorana fermions higher-order topology type-II Dirac semimetals

Current noises in a topological Josephson junction

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Science China(Physics,Mechanics & Astronomy) 2018年第9期61卷 75-81页

作者： Yu-Hang Li Jie Liu JunTao Song Hua Jiang Qing-Feng Sun XinCheng Xie International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Department of Applied Physics School of Science Xi'an Jiaotong University Xi'an 710049 China Department of Physics and Hebei Advanced Thin Film Laboratory Hebei Normal University Shijiazhuang 050024 China College of Physics Optoelectronics and Energy Soochow University Suzhou 215006 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

We study the transport properties of a superconductor-quantum spin Hall insulator-superconductor Josephson junction both in the absence and in the presence of a DC bias voltage. As the system is predicted to host majorana fermions at its interfaces,the Andreev bond states are supposed to exhibit a distinct 4π periodicity in the superconducting phase difference, namely the fractional Josephson effect. Using the non-equilibrium Green's function method, we calculate the current and the related current noise based on a tight-binding Hamiltonian. Our direct results show that the fractional Josephson effect can not be seen in equilibrium junctions. While in non-equilibrium junctions, this effect can be confirmed by the multiple Andreev reflections induced peaks of the non-equilibrium noise, which appear at discrete frequencies ω = ne V with n being an integer number.

关键词： majorana fermions Josephson junction current noise non-equilibrium Green's function

Chiral p-wave pairing of ultracold fermionic atoms due to a quadratic band touching

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Chinese Physics B 2018年第2期27卷 215-219页

作者：王海啸刘子衡蒋建华 College of Physics Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow University

We study the superfuild ground state of ultracold fermions in optical lattices with a quadratic band touching. Examples are a checkerboard lattice around half filling and a kagome lattice above one third filling. Instead of pairing between spin states, here we focus on pairing interactions between different orbital states. We find that our systems have only odd-parity （orbital） pairing instability while the singlet （orbital） pairing instability vanishes thanks to the quadratic band touching. In the mean field level, the ground state is found to be a chiral p-wave pairing superfluid （mixed with finite f-wave pairing order-parameters） which supports majorana fermions.

关键词： degenerate cold fermionic atoms topological states majorana fermions