Charge qubit

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Circuit diagram of a cooper pair box circuit. The island (dotted line) is formed by the gate capacitor and the junction capacitance.

A charge qubit is a superconducting qubit for quantum computing whose basis states are charge states (ie. states which represent the presence or absence of charge). A charge qubit is formed by a tiny superconducting island (also known as a Cooper-pair box) coupled by a Josephson junction to a superconducting reservoir (see figure). The state of the qubit is determined by the number of Cooper pairs which have tunneled across the junction. The charge qubit is typically read-out with an extremely sensitive electrometer such as the radio-frequency single-electron transistor.

Typical T1 times for a charge qubit are on the order of 1-2 μs.

External links

Lehnert, K. W., B. A. Turek, K. Bladh, L. F. Spietz, D. Gunnarsson, P. Delsing, and R. J. Schoelkopf, 2003, [Measurement of the excited-state lifetime of a microelectronic circuit], Physical Review Letters, Vol. 90, No. 2, January 2003

Quantum computing
Qubit | Quantum circuit | Quantum computer | Quantum cryptography | Quantum information | Quantum teleportation | Quantum virtual machine | Timeline of quantum computing
Nuclear magnetic resonance (NMR) quantum computing
Liquid-state NMR QC | Solid-state NMR QC
Photonic computing
Nonlinear optics | Linear optics QC | Non-linear optics QC | Coherent state based QC
Trapped ion quantum computers
NIST-type ion-trap QC | Austria-type ion-trap QC
Silicon-based quantum computing
Kane quantum computer
Superconducting quantum computing
Charge qubit | Flux qubit | Hybrid qubits

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