The University of Chicago

Amazon Technologies, Inc.

Yale University

Liang Jiang

Kyungjoo Noh

Oskar Jon Painter

Fernando Brandao

Steven M Girvin

Joseph Kramer Iverson

Harald Esko Jakob Putterman

Qian Xu

Chiao-Hsuan Wang

José Lebreuilly

Filip D Rozpedek

Cavity resonators are promising resources for quantum technology, while native nonlinear interactions for cavities are typically too weak to provide the level of quan¬ tum control required to deliver complex targeted operations. Here we investigate a scheme to engineer a target Hamiltonian for photonic cavities using ancilla qubits. By off-resonantly driving dispersively coupled ancilla qubits, we develop an optimized approach to engineering an arbitrary photon-number dependent (PND) Hamiltonian for the cavities while minimizing the operation errors. The engineered Hamiltonian admits various applications including canceling unwanted cavity self-Kerr interac¬ tions, creating higher-order nonlinearities for quantum simulations, and designing quantum gates resilient to noise. Our scheme can be implemented with coupled microwave cavities and transmon qubits in superconducting circuit systems.

Photon-number dependent Hamiltonian engineering for resonators

Quantum repeaters and network architectures use two concatenated quantum error correction codes to increase the transmission range of quantum information. A block of data qubits collectively encode a second-layer logical qubit according to a second-layer code concatenated with a first-layer code. A first-layer quantum repeater first-layer corrects each data qubit based on a first-layer syndrome extracted therefrom. The first-layer quantum repeater transmits these first-layer-corrected qubits to a second-layer quantum repeater via a quantum communication channel. The first-layer quantum repeater also transmits the first-layer syndromes to the second-layer quantum repeater via a classical communication channel. After extracting a second-layer syndrome from the first-layer-corrected qubits, the second-layer quantum repeater uses the first-layer syndromes and second-layer syndrome to second-layer correct the first-layer-corrected qubits. The first-layer syndromes improve quantum error correction by reducing the number of sec-and-layer stabilizer measurements needed to determine which data qubits have an error.

Quantum repeaters for concatenated quantum error correction, and associated methods

Selective frequency dissipation is implemented that enables cooling of energy gap protected qubits such that excited energy states resulting from heating or other undesired processes are returned to a lower excited energy state or a ground state manifold, thus reducing the probability of errors. Also, the selective frequency dissipation inhibits leakage from the energy gap protected qubits when in the ground state.

Frequency selective photon dissipation for an energy gap protected qubit

Growing community of inventors

Chicago, IL, United States of America

Liang Jiang