Quantum optics crucially relies on sources of quantum states of electromagnetic radiation. In this work, we demonstrate a source of entangled modes of microwave radiation that is fully deterministic, coherent, versatile, and scalable. Full quantum state tomography is performed up to 4 modes, and process maps of the sequential emission process allow us to find entanglement lengths of order ten photonic qubits.

Parity is an important statistic of physical systems. Here, we go beyond single photon detection and measure the parity of radiation reflected from a detector in single shot. We showcase the parity measurement on Fock states, demonstrate direct Wigner tomography of itinerant quantum light fields, and generate Schrödinger cat states.

Information is often transmitted using electromagnetic radiation, the quantum units of which are photons. In the microwave regime, detecting single itinerant photons at the receiving end of a transmission channel is challenging since microwave photons possess 5 orders of magnitude less energy than their optical counterparts. In this work, we show how to transfer the information content of a propagating photon into an excitation of a stationary qubit. By reading out the state of the latter, we acquire knowledge about the photon’s presence without destroying it. This ‘non-demolition’ aspect opens up new possibilities of detecting the photon in flight while allowing it to travel on towards another destination.

Realization of a universal quantum gate set for itinerant microwave photons.

A two-qubit C-PHASE gate implemented with tunable ZZ interactions.

A primary thermometer for microwave transmission lines, requiring only a very basic setup.

A study of two-photon resonance fluorescence, and Mollow-like triplets, by driving an artificial atom at the two-photon transition between its ground and second-excited state.

A system of two driven-dissipative nonlinear resonators, showing a crossover between an ordered state and a delocalized phase of photons.

How cascade decay of a ladder-type 3-level atom leads deterministically to entangled photon pairs, that we can spatially separate.

A superconducting switch, able to route quantum fields on chip with low loss, fast switching time, and high compression point.

Remote entanglement between two superconducting chips housed in separated cryogenic systems.

An all-microwave gate between two far detuned superconducting qubits.

Loss detection in quantum communication via time-bin encoding of information.

Ancilla-based parity measurement, and real-time feedback, demonstrating entanglement stabilization.

High-fidelity, low crosstalk, fast, readout of up to 5 superconducting circuits in a multiplexed circuit.

A fast, unconditional, all-microwave reset of superconducting qubits.

Deterministic remote entanglement between two superconducting atoms based on separate chips.