Mini Symposium on Quantum Technology

Join us for a series of talks from leading experts in Quantum Technologies.

Thursday, June 12, 9:00 - 12:00,  Albanova, Room FA32 ; and Albanova Collquium at 15:15-16:15, Oscar Klein Sal

9:00 - 9:45 Barbara Terhal  - QuTech, Delft University of Technology

Theory ideas which make quantum error correction easier in the lab 

The talk will discuss the idea of relaxing hardware requirements, first suggested for the surface code in Ref. [1], using so-called morphing or dynamic circuits. I present the feasibility and advantages of this approach to quantum error correcting circuits for a much wider class of error correction codes.
[1] M. McEwen, D. Bacon, C. Gidney, Relaxing Hardware Requirements for Surface Code Circuits using Time-dynamics, Quantum 7, 1172 (2023)
[2] M. Shaw and B.M. Terhal, Lowering Connectivity Requirements For Bivariate Bicycle Codes Using Morphing Circuits, Physical Review Letters, 134(9), 090602 (2025)

9:45 - 10:30  Andreas Wallraff  - ETH Zurich

Modular Approaches to Quantum Information Processing with Superconducting Circuits

Superconducting circuits are a strong contender for realizing quantum computing systems. Constructing such systems with many thousands, possibly millions of superconducting qubits will likely require linking several computing nodes housed in their dedicated cryogenic systems into a larger networked cluster. Such networks could operate at optical frequencies using fiber links but would require large bandwidth and high-fidelity microwave-to-optical conversion. At ETH Zurich, in a radically different approach, we have designed, realized, and tested a first quantum microwave link which allows superconducting-circuit-based quantum processors located in different systems to directly exchange quantum information [1] over distances of up to 30 meters as demonstrated in a loophole-free Bell test [2]. This link, for a quantum computer, takes the role of a network transferring data between computing nodes located in a high-performance computing data center. However, unlike its conventional counterparts, our data link is operated at ultra-low temperatures, close to absolute zero. This allows our quantum data link to directly connect to quantum processors operating at the same temperature [3]. Using this system, we transfer qubit states and generate entanglement on demand with high transfer and target state fidelities. The system we have constructed is the first of its kind in the world and could play an important role in both growing the power of quantum computers in the future and allowing for fundamental quantum science experiments.

[1] P. Magnard et al., Phys. Rev. Lett. 125, 260502 (2020)
[2] S. Storz et al., Nature 617, 265-270 (2023)
[3] P. Kurpiers et al., Nature 558, 264-267 (2018)

10:30 - 11:00  - Coffee break

11:00 - 11:45 - Antoine Browaeys  - Institute d'Optique, France

Assembling quantum matter one atom at a time

Over the last twenty years, physicists have learned to manipulate individual quantum objects: atoms, ions, molecules, quantum circuits, electronic spins... It is now possible to build "atom by atom" a synthetic quantum matter. By controlling the interactions between atoms, one can study the properties of these elementary many-body systems: quantum magnetism, transport of excitations, superconductivity... and thus understand more deeply the N-body problem. More recently, it was realized that these quantum machines may find applications in the industry, such as finding the solution of combinatorial optimization problems.

15:15-16:15 Albanova Colloquium, Oscar Klein Sal

Prof. Klaus Mølmer , Niels Bohr Institute

Flying and stationary qubits – a cascaded systems approach

 With the scaling of quantum technologies to many separate material quantum components, we may have recourse to couple these systems by quantum radiation of light, microwaves or phonons. In future optical quantum processors, we may, conversely, need to manipulate the quantum states of radiation pulses by their interaction with non-linear stationary quantum components. Several physical processes have been proposed and already demonstrated for these tasks. There are, however, rather fundamental obstacles to the treatment of propagation of radiation in circuits for quantum computing. These obstacles include the general multimode character of propagating fields and the duration and spatial extent of useful light and microwave pulses. The talk will review recent developments of a cascaded master equation approach to deal theoretically with these obstacles, and it will present examples of new, unforeseen, possibilities for easy preparation and manipulation “on the fly” of quantum states of light and matter.