Fast adiabatic qubit gates using only σ z control

By John M. Martinis, M. Geller. 2014

171 citations recorded by the source corpus.

A controlled-phase gate was demonstrated in superconducting Xmon transmon qubits with fidelity reaching 99.4%, relying on the adiabatic interaction between the $|11\ensuremath{\rangle}$ and $|02\ensuremath{\rangle}$ states. Here we explain the theoretical concepts behind this protocol, which achieves fast gate times with only ${\ensuremath{\sigma}}_{z}$ control of the Hamiltonian, based on a theory of nonlinear mapping of state errors to a power spectral density and use of optimal window functions. With a solution given in the Fourier basis, optimization is shown to be straightforward for practical cases of an arbitrary state change and finite bandwidth of control signals. We find that errors below ${10}^{\ensuremath{-}4}$ are readily achievable for realistic control wave forms.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/62fc7de5ec588fc8f8baf9dfaf2ffe7cbeb2aaaf

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Tunable Coupling Scheme for Implementing High-Fidelity Two-Qubit Gates (2018, methodology): “Finally, using optimized pulse shaping techniques [41] with our scheme can mitigate gate error from leakage and further improve fidelity.”
Tunable Superconducting Qubits with Flux-Independent Coherence (2017, background): “Here, both flux noise and off-resonant coupling to other qubits produce phase errors proportional to gate times, with the total gate error scaling as the square of the gate time [19].”
Digitized adiabatic quantum computing with a superconducting circuit (2015, background): “ure S1b shows the implementation of entangling, for example between qubits Q1 and Q0, we move Q0 to a higher frequency, and let Q1 undergo an adiabatic trajectory which is tuned to bring about a conditional phase shift while minimizing state leakage [56, 57].”
Shortcuts to adiabaticity: Concepts, methods, and applications (2019, background): “In particular Martinis and Geller (2014) considered a two-level model where only the σz term changes to achieve fast gates with the σx term constant in H = Hxσx + Hzσz.”