Noise in detection of qubit states using a quantum point contact

Neil Oxtoby; He-Bi Sun; Howard M. Wiseman

doi:10.1117/12.500397

8 May 2003 Noise in detection of qubit states using a quantum point contact

Neil Oxtoby, He-Bi Sun, Howard M. Wiseman

Proceedings Volume 5115, Noise and Information in Nanoelectronics, Sensors, and Standards; (2003) https://doi.org/10.1117/12.500397
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States

Abstract

We present a model for detection of the states of a coupled quantum dots (qubit) by a quantum point contact. Most proposals for measurements of states of quantum systems are idealized. However in a real laboratory the measurements cannot be perfect due to practical devices and circuits. The models using ideal devices are not sufficient for describing the detection information of the states of the quantum systems. Our model therefore includes the extension to a non-ideal measurement device case using an equivalent circuit. We derive a quantum trajectory that describes the stochastic evolution of the state of the system of the qubit and the measuring device. We calculate the noise power spectrum of tunnelling events in an ideal and a non-ideal quantum point contact measurement respectively. We found that, for the strong coupling case it is difficult to obtain information of the quantum processes in the qubit by measurements using a non-ideal quantum point contact. The noise spectra can also be used to estimate the limits of applicability of the ideal model.

Citation Download Citation

Neil Oxtoby, He-Bi Sun, and Howard M. Wiseman "Noise in detection of qubit states using a quantum point contact", Proc. SPIE 5115, Noise and Information in Nanoelectronics, Sensors, and Standards, (8 May 2003); https://doi.org/10.1117/12.500397

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KEYWORDS

Quantum communications

Quantum dots

Stochastic processes

Quantum information

Systems modeling

Quantum physics

Instrument modeling

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