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We study dephasing of electrons induced by a which path detector and thus verify Bohr's complementarity principle for fermions. We utilize a double path interferometer with two slits, with one slit being replaced by a coherent quantum dot…

量子物理 · 物理学 2009-10-30 E. Buks , R. Schuster , M. Heiblum , D. Mahalu , V. Umansky

Decoherence in superconducting qubits is known to arise because of a variety of environmental degrees of freedom. In this article, we focus on the influence of thermal fluctuations in a weakly damped circuit resonance coupled to the qubit.…

介观与纳米尺度物理 · 物理学 2007-05-23 P. Bertet , I. Chiorescu , C. J. P. M Harmans , J. E. Mooij

Dephasing -- phase randomization of a quantum superposition state -- is a major obstacle for the realization of high fidelity quantum logic operations. Here, we implement a two-qubit Controlled-NOT gate using dynamical decoupling (DD),…

量子物理 · 物理学 2013-07-17 Ch. Piltz , B. Scharfenberger , A. Khromova , A. F. Varón , Ch. Wunderlich

We propose a new device to create a tunable all-electric spin polarizer: a quantum point contact (QPC) with four gates -- two in-plane side gates in series. The first pair of gates, near the source, is asymmetrically biased to create spin…

介观与纳米尺度物理 · 物理学 2015-06-15 J. Charles , N. Bhandari , J. Wan , M. Cahay , R. S. Newrock

Periodic driving and Floquet engineering have emerged as invaluable tools for controlling and uncovering novel phenomena in quantum systems. In this study, we adopt these methods to manipulate nonequilibrium processes within…

量子物理 · 物理学 2023-09-12 Jakob Bätge , Yu Wang , Amikam Levy , Wenjie Dou , Michael Thoss

Effects of a bias electric current have been theoretically investigated in a spin-triplet superconducting ring in a magnetic field. Based on the Ginzburg-Landau theory, we show that the bias current can stabilize a half-quantum-flux (HQF)…

超导电性 · 物理学 2023-08-08 Kazushi Aoyama

We demonstrate a mesoscopic spin polarizer/analyzer system that allows the spin polarization of current from a quantum point contact in an in-plane magnetic field to be measured. A transverse focusing geometry is used to couple current from…

介观与纳米尺度物理 · 物理学 2009-11-07 R. M. Potok , J. A. Folk , C. M. Marcus , V. Umansky

The zero-temperature magnetic field-dependent conductance of electrons through a one-dimensional non-interacting tight-binding chain with an interacting {\it side} dot is reviewed and analized further. When the number of electrons in the…

强关联电子 · 物理学 2007-05-23 M. E. Torio , K. Hallberg , C. Proetto

The supercurrent of a quantum point contact coupled to a nanomagnet strongly depends on the dynamics of the nanomagnet's spin. We employ a fully microscopic model to calculate the transport properties of a junction coupled to a spin whose…

超导电性 · 物理学 2015-06-04 C. Holmqvist , W. Belzig , M. Fogelström

We calculate supercurrent across a two-dimensional topological insulator subjected to an external magnetic field. When the edge states of a narrow two-dimensional topological insulator are hybridized, an external magnetic field can close…

介观与纳米尺度物理 · 物理学 2015-11-18 Alexander Zyuzin , Mohammad Alidoust , Jelena Klinovaja , Daniel Loss

We investigate the measurement-induced dephasing of a qubit coupled with a single-mode cavity in the vacuum limit. Dephasing of the qubit state takes place through the ntanglement of the qubit and the single probe photon sent to the cavity,…

介观与纳米尺度物理 · 物理学 2014-07-09 Young-Wan Kim , Kang-Ho Lee , Kicheon Kang

Detailed schemes are investigated for experimental verification of Quantum Zeno effect with a superconducting qubit. A superconducting qubit is affected by a dephasing noise whose spectrum is 1/f, and so the decay process of a…

量子物理 · 物理学 2013-05-29 Yuichiro Matsuzaki , Shiro Saito , Kosuke Kakuyanagi , Kouichi Semba

Pumping of electrons through nano-scale devices is one of the fascinating achievements in the field of nano-science with a wide range of applications. To optimize the performance of pumps, operating them at high frequencies is mandatory. We…

介观与纳米尺度物理 · 物理学 2012-08-07 Alexander Croy , Ulf Saalmann

We investigate second-order magnetic responses of quantum magnets against ac magnetic fields. We focus on the case where the $z$ component of the spin is conserved in the unperturbed Hamiltonian and the driving field is applied in the $xy$…

强关联电子 · 物理学 2022-05-23 Tatsuya Kaneko , Yuta Murakami , Shintaro Takayoshi , Andrew J. Millis

We study the backaction of a driven nonlinear resonator on a multi-level superconducting qubit. Using unitary transformations on the multi-level Jaynes-Cummings Hamiltonian and quantum optics master equation, we derive an analytical model…

量子物理 · 物理学 2012-02-09 Maxime Boissonneault , A. C. Doherty , F. R. Ong , P. Bertet , D. Vion , D. Esteve , A. Blais

We develop a theory for two quasiparticle-induced decoherence mechanisms of a driven superconducting qubit. In the first mechanism, an existing quasiparticle (QP) tunnels across the qubit's Josephson junction while simultaneously absorbing…

Fast magnetization reversal of uniaxial Stoner particles by spin-transfer torque due to the spin-polarized electric current is investigated. It is found that a current with a properly designed time-dependent polarization direction can…

材料科学 · 物理学 2015-06-25 Z. Z. Sun , X. R. Wang

A quantum pump device involving magnetic barriers produced by the deposition of ferro magnetic stripes on hetero-structure's is investigated. The device for dc- transport does not provide spin-polarized currents, but in the adiabatic…

量子物理 · 物理学 2007-05-23 Ronald Benjamin , Colin Benjamin

A completely depolarising quantum channel always outputs a fully mixed state and thus cannot transmit any information. In a recent Letter [D. Ebler et al., Phys. Rev. Lett. 120, 120502 (2018)], it was however shown that if a quantum state…

量子物理 · 物理学 2020-09-25 Alastair A. Abbott , Julian Wechs , Dominic Horsman , Mehdi Mhalla , Cyril Branciard

Renormalized tunnel splitting with a finite distribution in the biaxial spin model for molecular magnets is obtained by taking into account the dipolar interaction of enviromental spins. Oscillation of the resonant tunnel splitting with a…

强关联电子 · 物理学 2009-11-07 Zhi-De Chen , J. -Q. Liang , Shun-Qing Shen