T. L. Robertson

Solid-state qubits with current-controlled coupling

The ability to switch the coupling between quantum bits (qubits) on and off is essential for implementing many quantum-computing algorithms. We demonstrated such control with two flux qubits coupled together through their mutual inductances and through the dc superconducting quantum interference device (SQUID) that reads out their magnetic flux states. A bias current applied to the SQUID in the zero-voltage state induced a change in the dynamic inductance, reducing the coupling energy controllably to zero and reversing its sign.

Decoherence in Josephson-junction qubits due to critical-current fluctuations

We compute the decoherence caused by

Flux Qubits and Readout Device with Two Independent Flux Lines

1∕f

Low-noise computer-controlled current source for quantum coherence experiments

fluctuations at low frequency

Quiet Readout of Superconducting Flux States

f

Superconducting quantum interference device with frequency-dependent damping : Readout of flux qubits

in the critical current

Quantum theory of three-junction flux qubit with non-negligible loop inductance : Towards scalability

{I}_{0}

Superconducting device to isolate, entangle, and read out quantum flux states

of Josephson junctions incorporated into flux, phase, charge, and hybrid flux-charge superconducting quantum bits (qubits). The dephasing time

Variable Coupling of Two Flux Qubits

{\ensuremath{\tau}}_{\ensuremath{\phi}}

Measurements of Dephasing in Superconducting Flux Qubits

scales as