相关论文: Multiple and single measurements of a mesoscopic q…
Multiple and single measurements of quantum states of mesoscopic superconducting loops are carried out in order to investigate a possibility of macroscopic quantum superposition and of creation of a superconductor quantum register.…
The current-voltage curves and magnetic dependence of the critical current of asymmetric superconducting loops are measured. It was found that sign and value of the asymmetry of the current-voltage curves changes with value of magnetic…
We have observed coherent time evolution of states in a multi-level quantum system, formed by a current-biased dc SQUID. The manipulation of the quantum states is achieved by resonant microwave pulses of flux. The number of quantum states…
The paper discusses dynamics of quantum measurements in mesoscopic solid-state systems. The aim is to show how the general ideas of the quantum measurement theory play out in the realistic models of actual mesoscopic detectors. The two…
Despite an apparent progress in implementing individual solid-state qubits, there have been no experimental reports so far on multi-bit gates required for building a real quantum computer. Here we report a new circuit comprising two coupled…
The possibility of making a flux qubit on nonsuperconducting mesoscopic ballistic quasi 1D ring is discussed. We showed that such ring can be effectively reduced to a two-state system with two external control parameters. The two states…
The quantum oscillations in magnetic field of the critical current of asymmetric superconducting rings with different widths of the half-rings are shifted to opposite sides for measurement in the opposite direction. The value of this shift…
Ten years ago, coherent oscillations between two quantum states of a superconducting circuit differing by the presence or absence of a single Cooper pair on a metallic island were observed for the first time. This result immediately…
We show that a superconducting circuit containing two loops, when treated with Macroscopic Quantum Coherence (MQC) theory, constitutes a complete two-bit quantum computer. The manipulation of the system is easily implemented with…
The states of two phase-coupled superconducting rings have been investigated. Multiple current states have been revealed in the dependence of the critical current on the magnetic field. The performed calculations of the critical currents…
We study fluctuations of conductance of two connected in series dots in the Coulomb blockade regime. The pattern of the fluctuations turns out to be extremely sensitive to a magnetic field. These conductance fluctuations also provide…
A microscopic model is constructed which is able to describe multiple magnetic flux transitions as observed in recent ultra-low temperature tunnel experiments on an aluminum superconducting ring with normal metal - insulator -…
We have observed multiphoton transitions between two macroscopic quantum-mechanical superposition states formed by two opposite circulating currents in a superconducting loop with three Josephson junctions. Resonant peaks and dips of up to…
We have studied theoretically the basic operation of a quantum feedback loop designed to maintain the desired phase of quantum coherent oscillations in a two-level system. Such feedback can suppress the dephasing of oscillations due to…
We consider the problem of continuous quantum measurement of coherent oscillations between two quantum states of an individual two-state system. It is shown that the interplay between the information acquisition and the backaction dephasing…
We have observed coherent time evolution between two quantum states of a superconducting flux qubit comprising three Josephson junctions in a loop. The superposition of the two states carrying opposite macroscopic persistent currents is…
The notion of a macroscopic quantum state must be pinned down in order to assess how well experiments probe the large-scale limits of quantum mechanics. However, the issue of quantifying so-called quantum macroscopicity is fraught with…
Two basic physical models, a two-level system and a harmonic oscillator, are realized on the mesoscopic scale as coupled qubit and resonator. The realistic system includes moreover the electronics for controlling the distance between the…
Quantum coherence of electrons interacting via the magnetostatic coupling and confined to a mesoscopic cylinder is discussed. The electromagnetic response of a system is studied. It is shown that the electromagnetic kernel has finite low…
State readout is a key requirement for a quantum computer. For semiconductor-based qubit devices it is usually accomplished using a separate mesoscopic electrometer. Here we demonstrate a simple detection scheme in which a radio-frequency…