S.O. Mundhada

Robust Concurrent Remote Entanglement Between Two Superconducting Qubits

Entangling two remote quantum systems which never interact directly is an essential primitive in quantum information science and forms the basis for the modular architecture of quantum computing. When protocols to generate these remote entangled pairs rely on using traveling single photon states as carriers of quantum information, they can be made robust to photon losses, unlike schemes that rely on continuous variable states. However, efficiently detecting single photons is challenging in the domain of superconducting quantum circuits because of the low energy of microwave quanta. Here, we report the realization of a robust form of concurrent remote entanglement based on a novel microwave photon detector implemented in the superconducting circuit quantum electrodynamics (cQED) platform of quantum information. Remote entangled pairs with a fidelity of

Continuous Quantum Nondemolition Measurement of the Transverse Component of a Qubit

0.57\pm0.01

Coherent oscillations inside a quantum manifold stabilized by dissipation

are generated at

Multimode cat codes

200

Generating higher order quantum dissipation from lower order parametric processes

Hz. Our experiment opens the way for the implementation of the modular architecture of quantum computation with superconducting qubits.

Pair-cat codes: autonomous error-correction with low-order nonlinearity.

Quantum jumps of a qubit are usually observed between its energy eigenstates, also known as its longitudinal pseudospin component. Is it possible, instead, to observe quantum jumps between the transverse superpositions of these eigenstates? We answer positively by presenting the first continuous quantum nondemolition measurement of the transverse component of an individual qubit. In a circuit QED system irradiated by two pump tones, we engineer an effective Hamiltonian whose eigenstates are the transverse qubit states, and a dispersive measurement of the corresponding operator. Such transverse component measurements are a useful tool in the driven-dissipative operation engineering toolbox, which is central to quantum simulation and quantum error correction.