Microwave Electronics in Quantum Computers

Zenghui Bao, Yan Li, Zhiling Wang +7 more

For superconducting quantum processors, microwave signals are delivered to each qubit from room-temperature electronics to the cryogenic environment through coaxial cables. Limited by the heat load of cabling and the massive cost of electronics, such an architecture is not viable for millions of qubits required for fault-tolerant quantum computing. Monolithic integration of the control electronics and the qubits provides a promising solution, which, however, requires a coherent cryogenic microwave pulse generator that is compatible with superconducting quantum circuits. Here, we report such a signal source driven by digital-like signals, generating pulsed microwave emission with well-controlled phase, intensity, and frequency directly at millikelvin temperatures. We showcase high-fidelity readout of superconducting qubits with the microwave pulse generator. The device demonstrated here has a small footprint, negligible heat load, great flexibility to operate, and is fully compatible with today's superconducting quantum circuits, thus providing an enabling technology for large-scale superconducting quantum computers.

James J. Raftery, Andrei Vrajitoarea, Gengyan Zhang +3 more

Yiran Tian

In this dissertation, resonator-based readout techniques were developed for floating electrons as qubits on cryogenic substrates, using two platforms: electrons on liquid helium and electrons on solid neon. In addition, a cryogenic microwave source was developed to enable low-noise measurement for qubit readout.

Lev Krayzman, Chan U Lei, T. Brecht +5 more

Mark Buchanan

A new device converts a stream of microwave photons into an electric current with high efficiency, which will benefit quantum information technologies.By Mark Buchanan T echnologies for quantum computing, sensing, and communication process information stored in quantum bits (qubits) by using microwave photons.But detecting such photons accurately and at high rates-to read out the changing states of a quantum computer, for example-is a challenge, since they have much less energy than visible or infrared photons.Now researchers have demonstrated a Help arrives.This schematic image shows a microwave photon (red) being transmitted through an antenna-like wire made of granular aluminum called a resonator to a tunnel junction (intersection of the gray bars).The absorption of this photon by an electron (sphere) allows the electron to cross the junction, where it signals the presence of the photon.Detecting microwave photons rapidly and efficiently will be essential for future quantum information technologies

Matti Partanen, Kirill G. Fedorov, Stefan Pogorzalek +5 more