Quantum Computation with Persistent-current Aharonov-Bohm Qubits and Qugates

Igor O. Kulik
Bilkent University, TR

Keywords: qubit, persistent, CNOT

Abstract:
We propose that Aharonov-Bohm effect can be used for quantum computation. The effect consists of existence of persistent currents in mesoscopic/nanoscopic loops of normal metal or semiconductor in a magnetic field perpendicular to loop. Three-site loop formed by three metallic islands coupled via resonant tunneling satisfy all criteria for basic element of quantum computer, the qubit. Persistent- current qubit performs all necessary transformations of quantum logic gate (qugate) under the effect of static electric field applied perpendicular to magnetic field. Electric voltages in form of pulses of prescribed duration accomplish phase and bit flips (NOT gate), the Hadamard gate, initialization, and also the controlled NOT transformation (the CNOT gate) when persistent current in the qubit No.1 is nondemlition-measured by a mesoscopic Quantum Hall bar in form of a Corbino disk between two near qubits, and transformed to a voltage operating the qubit No.2. The qugate operations are therefore effected by a radiation free couplings between the qubits making persistent-current qubits scalable elements in a quantum network. Possible physical realizations of the Aharonov-Bohm qubits are discussed.

NSTI Nanotech 2003 Conference Technical Program Abstract