Big congrats to Rishabh Sahu for winning this years Carl E. Anderson Division of Laser Science Dissertation Award of the American Physical Society:

“For realizing a high-cooperativity electro-optic interconnect demonstrating ultra-low noise conversion and the first observation of microwave-optical entanglement, thus laying the experimental foundations for the new field of cavity quantum electro-optics.”

A great honor and well deserved!

Check out our new article in Science (open access reprint).

Editor’s summary: Several platforms are under development for quantum computation, simulation, and metrology applications, with each platform operating at different operational wavelengths for optimized performance. For practical technologies, the reality will likely be a hybrid of platforms that require quantum entanglement to be generated and shared across platforms with a large energy disparity. Sahu et al. introduce an electro-optical device that allows the generation of quantum entanglement between microwaves (the operational wavelengths of superconducting circuits) with optical photons (the operational wavelength of long-distance quantum communication). Bridging platforms with more than five orders of magnitude difference in energy scales and maintaining the fragile entanglement provides a route to efficiently linking up hybrid quantum systems. — Ian S. Osborne

More info on the ISTA website: “Wiring up Quantum Circuits with Light“

Rishabh successfully defended his PhD thesis!

He is at the center of our team laying the ground for “Cavity quantum electrooptics” exploring quantum-limited interactions between microwaves and light. Impressive work – and impressive hat!

Congrats Elena who successfully defended her PhD thesis about multi-transmon devices in waveguides and cavities. Big thanks to Will Oliver who joined us and gave an excellent talk at ISTA.

As major corporations scale up noisy qubit systems there is a growing need for better qubits to avoid excessive error-correction overheads. Very happy to announce our new NOMIS Foundation project: Protected States of Quantum Matter starting next year together with Giorgos Katsaros’ and Andrew Higginbotham’s groups @ISTAustria. We will be working together toward addressing some of the fundamental questions related to intrinsic and non-local quantum information protection on the hardware level.
Being part of the amazing NOMIS family will allow us to follow unexpected directions, be transparent with our data and inventions, and interpret the results in an unbiased way.

Big congrats to Matilda for successfully defending her PhD thesis on “Geometric superinductors and their applications in circuit quantum electrodynamics“.

A big THANK YOU to all speakers and CONGRATS to our Rishabh Sahu who won the poster cash prize for his contribution: “Quantum-enabled microwave optical interface with unity internal efficiency”.

Nice outreach piece summarizing our two recent results on optical interfaces for superconducting quantum processors at IST Austria News.

G. Arnold*, M. Wulf*, S. Barzanjeh, E. S. Redchenko, A. Rueda, W. J. Hease, F. Hassani, and J. M. Fink. 2020. Converting microwave and telecom photons with a silicon photonic nanomechanical interface. Nature Communications. DOI: 10.1038/s41467-020-18269-z

William Hease*, Alfredo Rueda*, Rishabh Sahu, Matthias Wulf, Georg Arnold, Harald G. L. Schwefel, and Johannes M. Fink. 2020. Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State. PRX Quantum. DOI: 10.1103/PRXQuantum.1.020315

We are witnessing rapid progress in the fields of quantum computing with superconducting circuits on the one hand, and long-distance optical quantum communication on the other. Meanwhile, there is currently no solution to interface these two domains of quantum technology in analogy to fiber optic modems in classical communication systems. Apart from close to unity efficiency and high bandwidth, such a quantum interface also needs to operate close to its quantum ground state with hardly any excess noise on either the electrical or the optical output—an important milestone that we demonstrate in this work.

We realize the electro-optic wavelength converter based on a mechanically polished crystalline lithium niobate whispering gallery mode resonator. In contrast to traditional modulators, the interaction is resonantly enhanced using a superconducting microwave cavity that matches the free spectral range and leads to an extremely efficient bidirectional conversion process. We show that this conversion works well despite the relatively high optical pump powers required. The microwave mode remains close to the quantum ground state at millikelvin temperatures where superconducting qubits operate.

The centimeter-sized device benefits from a large heat capacity and a good thermalization to the cold environment, resulting in an extremely slow observed heating rate compared to on-chip devices. Based on this, we estimate that pulsing the pump can boost the conversion efficiency by another 4 orders of magnitude without a significant increase of added noise. This would open the way for long-distance quantum networks utilizing superconducting processors for secure communication and distributed quantum computing.

Bidirectional electro-optic wavelength conversion in the quantum ground state
W. Hease*, A. Rueda*, R. Sahu, M. Wulf, G. Arnold, H. G. L. Schwefel, J. M. Fink.
PRX Quantum 1, 020315 (2020)
PRXQ, arXiv

In superconducting circuits, superinductors are employed to suppress charge fluctuations and increase zero-point voltage, enabling features for hardware-protected qubits, metrological standards, and strongly coupled hybrid devices. Conventionally these devices are based on kinetic inductance, and can suffer from nonlinearity, additional complexity due to multiterminal structure, and the limited control and reliability of bottom-up fabrication. Making use of miniaturization and substrate engineering, the authors realize a geometrically defined, single-wavefunction superinductor—a high-performance, innovative circuit element that promises to expand the scope of quantum circuitry.

Surpassing the resistance quantum with a geometric superinductor
M. Peruzzo*, A. Trioni*, F. Hassani, M. Zemlicka, J. M. Fink
Phys. Rev. Applied 14, 044055 (2020)

News coverage: Geometric Inductor Breaks Resistance Quantum “Limit” Physics 13, 141 (2020)