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Kuo Hai

Publications and source records attributed to Kuo Hai.

6 recordsLinked to original sources

A Connectivity-Order Law and Conditional Minimal-Mechanism Identification in Many-Body Geometric Phases

The value of a multiqubit geometric phase at a single operating point does not reveal whether it was generated directly or through a connected sequence of lower-body interactions. For analytic, gapped, nondegenerate Abelian holonomies, we jointly resolve logical support and independently calibrated coupling support. Every nonzero connected response must involve an active set that connects and covers the target and must contain one factor of each active coupling, yielding the sharp onset bound $\nu_S \geq \tau_E(S)$. The same selection law applies locally to projected Berry curvature. Conversely, an unrestricted finite-dimensional construction realizes all responses allowed by the connected-cover condition simultaneously, making the condition necessary and sufficient within this theorem class. Operationally, simultaneous confidence bands certify detected mixed responses while controlling false positives; a factor-of-two separation condition additionally recovers exact library-relative response minima. In a complete dictionary, nontriviality of every minimal-cover response is generically necessary and sufficient for these minima to coincide with the minimal calibrated mechanisms. Three-qubit Wilson calculations distinguish direct and pair-mediated routes with the same endpoint phase, and a synthetic Ramsey audit locates the finite-resolution boundary.

quant-ph

Coherently controlling robust spin-orbit qubits of electrons in nanowire quantum dots

We consider an electron confined in a gated nanowire quantum dot (NQD) with arbitrarily strong spin-orbit coupling (SOC) and weak static magnetic field, and treat the latter as a perturbation to seek the maximal spin-motion entangled states with the exact general solutions of the perturbed equations. From the boundedness and self-consistent conditions of the general solutions we find two corrected energies to any n level of the unperturbed system with ground state n = 0, which are much less than the unperturbed level-difference and corresponds to a spin-orbit qubit. We demonstrate the metastability of the two-level states and the decoherence-averse effect of SOC, and suggest an alternative scheme to perform the qubit control, simply by adjusting the orientation of magnetic field for any fixed SOC. Such a adjustment can lead to the spin flipping of the state vector and the position exchanging of the probability-density wavepackets which can be proposed as the non-Abelian quasiparticles. The results could be directly extended to a weakly coupled array of NQDs for coherently encoding the robust spin-orbit qubits.

cond-mat.mes-hall

Electronic transport property of PbS nanowire devices

Lead sulfide is an important photosensitive material, and its photoelectric properties have received widespread attention. We completed the preparation of PbS nanowires and single PbS nanowire devices, then we conducted electrical performance tests on the PbS nanowire devices. We found that a single lead sulfide nanowire device exhibits memristive properties that depend on the applied voltage and the power density of light. From this we studied the electrical transport properties of single lead sulfide nanodevices.

physics.app-ph

Braiding a novel kind of Majorana-like quasiparticles in nanowire quantum dots

For an electrically driven electron confined in a nanowire quantum dot with spin-orbit coupling (SOC), we find a SOC-magnetism phase-locked condition under which we derive a complete set of Schrödinger kitten states which contains some novel degenerate ground states with oscillating wave packets or stationary double packets in undriven case. We identify such wave packets as Majorana-like quasiparticles and demonstrate that they obey non-Abelian statistics and behave similarly to neutral particles. The braiding operations based on the interchanges of the degenerate non-Abelian quasiparticles are shown, which shift the system between different ground states and may be insensitive to perturbations and weak noise from the environment. The results could be tested experimentally in the existing setups and could be treated as the leading-order results to directly extended to an array of weakly coupled single-electron quantum dots for topological quantum computation.

cond-mat.mes-hall

A novel exact solution to transmission problem of electron wave in a nonlinear Kronig-Penney superlattice

Nonlinear Kronig-Penney model has been frequently employed to study transmission problem of electron wave in a nonlinear electrified chain or in a doped semiconductor superlattice. Here from an integral equation we derive a novel exact solution of the problem, which contains a simple nonlinear map connecting transmission coefficient with system parameters. Consequently, we suggest a scheme for manipulating electronic distribution and transmission by adjusting the system parameters. A new effect of quantum coherence is evidenced in the strict expression of transmission coefficient by which for some different system parameters we obtain the similar aperiodic distributions and arbitrary transmission coefficients including the approximate zero transmission and total transmission, and the multiple transmissions. The method based on the concise exact solution can be applied directly to some nonlinear cold atomic systems and a lot of linear Kronig-Penney systems, and also can be extended to investigate electron transport in different discrete nonlinear systems.

quant-ph

Phase-controlled localization and directed transport in a bipartite lattice

We investigate coherent control of single particles held in a bipartite optical lattice via a combined high-frequency modulation. Our analytical results show that for the photon resonance case the quantum tunneling and dynamical localization depend on the phase difference between the modulation components, which leads to a different route of the coherent destruction of tunneling and a simple method for stabilizing the system to implement the directed transport. The results could be referable for manipulating the transport characterization of the similar tilted and shaken optical or solid-state systems, and also can be extended to the many-particle systems.

quant-ph