Implementing a universal gate set on a logical qubit encoded in an oscillator

By R. Heeres, P. Reinhold, N. Ofek, Luigi Frunzio, Liang Jiang, Michel H. Devoret, Robert J. Schoelkopf. Nature Communications, 2016

344 citations recorded by the source corpus.

A logical qubit is a two-dimensional subspace of a higher dimensional system, chosen such that it is possible to detect and correct the occurrence of certain errors. Manipulation of the encoded information generally requires arbitrary and precise control over the entire system. Whether based on multiple physical qubits or larger dimensional modes such as oscillators, the individual elements in realistic devices will always have residual interactions, which must be accounted for when designing logical operations. Here we demonstrate a holistic control strategy which exploits accurate knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system. We use this approach to realize high-fidelity (98.5%, inferred), decoherence-limited operations on a logical qubit encoded in a superconducting cavity resonator using four-component cat states. Our results show the power of applying numerical techniques to control linear oscillators and pave the way for utilizing their large Hilbert space as a resource in quantum information processing. A logical qubit is a two-dimensional subspace of a higher dimensional system, whose manipulation requires precise control over the whole system. Here the authors demonstrate a control strategy which exploits precise knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system.

Subfields: Artificial Intelligence

View Paper: https://www.semanticscholar.org/paper/0952fff68b289817b5e6b99e22d4cbd5600e8cad

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Citations in the corpus

Quantum optimal control in quantum technologies. Strategic report on current status, visions and goals for research in Europe (2022, methodology): “Starting with superconducting circuit platforms, QOCT has been used to prepare logical qubits encoded in bosonic modes [442] and to implement quantum gates [283, 413, 616, 628, 665].”
Coherent oscillations inside a quantum manifold stabilized by dissipation (2017, methodology): “Our gate is fundamentally different than previous manipulations of Schrödinger cat states [17] as it operates while the manifold is stabilized.”
Circuit quantum electrodynamics (2020, positive): “Combining these ideas with numerical optimal control has allowed Heeres et al. (2017) to synthesize cavity states with high fidelity such as Fock states up to |n = 6〉 and four-legged cat states.”
Quantum information processing and quantum optics with circuit quantum electrodynamics (2020, methodology): “The interaction of each qubit with the oscillator takes the form of ^ H coupling I and multiple approaches have been theoretically proposed and experimentally implemented to turn this qubit-resonator coupling into an effective qubit–qubit interaction 19,25,47 .”
Widely Tunable On-Chip Microwave Circulator for Superconducting Quantum Circuits (2017, background): “The first demonstrations of operations on single logical qubits [48, 49] were made this year with superconducting circuits.”
Performance and structure of single-mode bosonic codes (2017, background): “, microwave cavity [118], atomic ensemble [119,120], and trapped ion [121] control, suggest that making these states may be within reach.”
Quantum information processing with superconducting circuits: a review (2016, methodology): “Heeres et al [148] recently dem onstrated highfidelity implementation of a universal set of gates on a qubit encoded into an oscillator using the cat code, target ing the creation and manipulation of a logical qubit encoded in an evenparity fourcomponent cat subspace.”
Efficient Multiphoton Sampling of Molecular Vibronic Spectra on a Superconducting Bosonic Processor (2019, methodology): “A vacuum state of both bosonic modes is prepared through feedback cooling protocols, and Fock states jn;mi are initialized using optimal control techniques [12] (see Appendix D).”
Exponential suppression of bit or phase errors with cyclic error correction (2021, neutral): “[44] 2017 Cat States N/A 1 N/A superconducting”
Fast universal control of an oscillator with weak dispersive coupling to a qubit (2021, methodology): “We note that the cavity drive amplitudes used in our ECD gates are over an order-of-magnitude larger than typical cavity drive amplitudes used in optimized GRAPE pulses [37].”
Almost-linear time decoding algorithm for topological codes (2017, background): “Experimental efforts have made rapid progress in recent years [3, 41, 2, 15, 34, 14, 36, 49, 48, 40], and may soon have the capabilities to demonstrate small-scale error correction.”
Leakage reduction in fast superconducting qubit gates via optimal control (2020, methodology): “[19] Heeres, R.”