Simple Pulses for Elimination of Leakage in Weakly Nonlinear Qubits
Abstract
In realizations of quantum computing, a twolevel system (qubit) is often singled out from the many levels of an anharmonic oscillator. In these cases, simple qubit control fails on short time scales because of coupling to leakage levels. We provide an easy to implement analytic formula that inhibits this leakage from any singlecontrol analog or pixelated pulse. It is based on adding a second control that is proportional to the time derivative of the first. For realistic parameters of superconducting qubits, this strategy reduces the error by an order of magnitude relative to the state of the art, all based on smooth and feasible pulse shapes. These results show that even weak anharmonicity is sufficient and in general not a limiting factor for implementing quantum gates.
 Publication:

Physical Review Letters
 Pub Date:
 September 2009
 DOI:
 10.1103/PhysRevLett.103.110501
 arXiv:
 arXiv:0901.0534
 Bibcode:
 2009PhRvL.103k0501M
 Keywords:

 03.67.Lx;
 02.30.Yy;
 85.25.j;
 Quantum computation;
 Control theory;
 Superconducting devices;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity;
 Quantum Physics
 EPrint:
 4 pages, 4 figures