Optimized single-qubit gates for Josephson phase qubits

Abstract

In a Josephson phase qubit the coherent manipulations of the computational states are achieved by modulating an applied ac current, typically in the microwave range. In this work we show that it is possible to find optimal modulations of the bias current to achieve high-fidelity gates. We apply quantum optimal control theory to determine the form of the pulses and study in details the case of a NOT-gate. To test the efficiency of the optimized pulses in an experimental setup, we also address the effect of possible imperfections in the pulses shapes, the role of off-resonance elements in the Hamiltonian, and the effect of capacitive interaction with a second qubit.Comment: 10 pages, 13 figure

Multifrequency control pulses for multilevel superconducting quantum circuits

“…Optimal control theory has also been applied to this problem [13,14,15], and recent work has indicated that arbitrarily fast control is possible using certain choices of pulses [16]. The presence of higher levels is also problematic for coupled qubit operation.…”

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“…In quantum chemical, quantum optimal control made great success. Recent work has optimized the control law for closed or open system population transfer by using a gradient ascent pulse engineering algorithm [11,12]. Optimal control has been exploited to control the quantum decoherence, where an optimal control law was designed to effectively suppress decoherence effects in Markovian open quantum systems.…”

High-fidelity quantum gates in the presence of dispersion

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