相关论文: Nondemolition measurements of a single quantum spi…

Josephson current of spin-entangled electrons through the two branches of a SQUID-like structure with two quantum dots exhibits a magnetic-flux response different from the conventional Josephson current. Due to their interference, the…

We study the persistent current in a ring consisting of N >> 1 Josephson junctions threaded by the magnetic flux. When the dynamics of the ring is dominated by the capacitances of the superconducting islands the system is equivalent to the…

Supercurrent transport is experimentally studied in a Josephson junction hosting a double quantum dot (DQD) with tunable symmetries. The QDs are parallel-coupled to two superconducting contacts and can be tuned between strong inter-dot…

We study the Josephson-like spin currents between two ferromagnetic metals by deriving the effective action of the junction. A DC spin Josephson current with the full O(3) symmetry is obtained. By the analogy to the superconducting…

We propose and theoretically investigate spin superconducting qubits. Spin superconducting qubit consists of a single spin confined in a Josephson junction. We show that owing to spin-orbit interaction, superconducting difference across the…

Half a century after its discovery, the Josephson junction has become the most important nonlinear quantum electronic component at our disposal. It has helped reshape the SI system around quantum effects and is used in scores of quantum…

The concept of quantum nondemolition (QND) measurement is extended to coherent oscillations in an individual two-state system. Such a measurement enables direct observation of intrinsic spectrum of these oscillations avoiding the…

By coupling a harmonic oscillator to a quantum system it is possible to perform a dispersive measurement that is quantum non-demolition (QND), with minimal backaction. A non-linear oscillator has the advantage of measurement gain, but what…

Quantum simulators built from ultracold atoms promise to study quantum phenomena in interacting many-body systems. However, it remains a challenge to experimentally prepare strongly correlated continuous systems such that the properties are…

We extend the Keldysh formulation to quantum spin systems and derive exact equations of motion. This allows us to explore the dynamics of single spins and of ferromagnets when these are inserted between superconducting leads. Several new…

We calculate a nondissipative spin current and show that it can flow with or without a charge current. We consider a two-band model which can be applied to the description of Fe-based pnictides in coexistence regime of superconductivity and…

Measurement of quantum systems inevitably involves disturbance in various forms. Within the limits imposed by quantum mechanics, however, one can design an "ideal" projective measurement that does not introduce a back action on the measured…

In this proposal, we present an experimental setup based on superconducting circuits and Josephson junctions to explore the modification of Josephson coefficient in the presence of external magnetic field due to vacuum polarization of…

Transport is called nonreciprocal when not only the sign, but also the absolute value of the current, depends on the polarity of the applied voltage. It requires simultaneously broken inversion and time-reversal symmetries, e.g., by the…

We study a double quantum dot each dot of which is tunnel-coupled to superconducting leads. In the Coulomb blockade regime, a spin-dependent Josephson coupling between two superconductors is induced, as well as an antiferromagnetic…

We investigate experimentally the physics of quantum phase slips in one-dimensional Josephson Junction chains. These quantum phase-slips are induced by quantum phase fluctuations occurring on single junctions of the chain. In our experiment…

We use the Gross-Pitaevskii equation to study Josephson tunneling between two weakly coupled Bose-Einstein condensates, which compose spin-1 bosons. We show that a rotating magnetic field on one side can produce a phase difference across…

High quality factors, strong nonlinearities, and extensive design flexibility make superconducting circuits an ideal platform to investigate synchronization phenomena deep in the quantum regime. Recently~\cite{Loerch-2017}, it was predicted…

Recent experimental conductance measurements performed on paramagnetic molecular adsorbates on a superconducting surface, using superconducting scanning tunneling microscopy techniques, are theoretically investigated. For low temperatures,…

We show that the S/F/S Josephson $\varphi_0$-junction permits detection of macroscopic quantum tunneling and quantum oscillation of the magnetic moment by measuring the ac voltage across the junction. Exact expression for the tunnel…