Biomedical subjects

D Mozyrsky

Publications and source records attributed to D Mozyrsky.

5 recordsLinked to original sources

PubMed2004

Quantum-limited sensitivity of single-electron-transistor-based displacement detectors.

We consider a model of a quantum-mechanical resonator capacitively coupled to a single electron transistor (SET). The tunnel current in the SET is modulated by the vibrations of the resonator, and thus the system operates as a displacement detector. We analyze the effect of the backaction noise of charge fluctuations in the SET onto the dynamics of the resonator and evaluate the displacement sensitivity of the system. The relation between the "classical" and "quantum" parts of the SET charge noise and their effect on the measured system are also discussed.

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PubMed2003

Relaxation and the Zeno effect in qubit measurements.

We consider a qubit interacting with its environment and continuously monitored by a detector represented by a point contact. Bloch-type equations describing the entire system of the qubit, the environment, and the detector are derived. Using these equations we evaluate the detector current and its noise spectrum in terms of the decoherence and relaxation rates of the qubit. Simple expressions are obtained that show how these quantities can be accurately measured. We demonstrate that due to interaction with the environment, the measurement can never localize a qubit even for infinite decoherence rate.

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PubMed2003

A scheme for electrical detection of single-electron spin resonance.

We study a scheme for electrical detection of the spin resonance of a single-electron trapped near a field effect transistor (FET) conduction channel. In this scheme, the resonant Rabi oscillations of the trapped electron spin cause a modification of the average charge of a shallow trap, which can be detected through the change in the FET channel resistivity. We show that the dependence of the channel resistivity on the frequency of the rf field can have either peak or dip at the Larmor frequency of the electron spin in the trap.

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PubMed2002

Quantum-classical transition induced by electrical measurement.

A model of an electrical tunnel junction coupled to a mechanical system (oscillator) is studied to simulate the dephasing effect of measurement on a quantum system. The problem is solved at zero temperature under conditions of strong nonequilibrium in the measurement apparatus. For linear coupling between the oscillator and tunneling electrons, it is found that the oscillator dynamics becomes damped, with the effective temperature determined by the voltage drop across the junction. It is demonstrated that both the quantum heating and the quantum damping of the oscillator manifest themselves in the current-voltage characteristic of the tunnel junction.

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PubMed2001

Indirect interaction of solid-state qubits via two-dimensional electron gas.

We propose a mechanism of long-range coherent coupling between nuclear spin qubits in semiconductor-heterojunction quantum information processing devices. The coupling is via localized donor electrons which interact with the two-dimensional electron gas. An effective interaction Hamiltonian is derived and the coupling strength is evaluated. We also discuss mechanisms of decoherence and consider gate control of the interaction between qubits. The resulting quantum computing scheme retains all the control and measurement aspects of earlier approaches, but allows qubit spacing at distances of the order of 100 nm, attainable with the present-day semiconductor device technologies.

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