Josephson Parametric Circuits in Quantum Networks

Josephson Parametric Devices (JPDs), such as amplifiers and converters, emerged as essential building blocks and integral parts of modern superconducting quantum experiments operated in the GHz range of frequencies. JPDs may be used as quantum-limited preamplifiers, or as sources of highly nonclassical radiation, including quantum-entangled signals. Respectively, these properties are routinely exploited in high-fidelity readout schemes of various microwave quantum systems, including superconducting qubits, which is crucial for the development of quantum computing platforms. Furthermore, the ability of JPDs to generate vacuum-squeezed and entangled signals opens a complementary avenue for steady-state generation of quantum resource states, which can be exploited in emerging microwave quantum networks, reservoir quantum computing, and quantum sensing. Here, I will introduce basic principles and architectures of modern JPDs, as well as their state-of-the-art properties. I will discuss typical use cases, which include both fundamental and applied protocols, such as remote qubit entanglement and quantum teleportation, blind quantum computing, and quantum radar applications. Finally, I will present our recent results in microwave quantum communication over hot microwave channels using JPDs and map possible extensions to wireless, open-air microwave quantum key distribution at room temperatures.