WELCOME TO SUPERQULAN

Superconducting quantum circuits are one of the most promising platforms for realizing large-scale quantum computing devices, where in the near future a coherent integration of 100-1000 quantum bits (qubits) is feasible. However, the required temperatures of only a few mK currently restrict quantum operations to qubits that are located within a single, heavily shielded dilution refrigerator. This imposes a serious constraint on the realization of even larger quantum processors or the implementation of local- and wide-area quantum networks based on this technology.

The project SuperQuLAN is set out to address this important open problem and to demonstrate a first operational prototype quantum local area network (QuLAN) of separated superconducting quantum processors. This work will be carried out by a multi-national team of scientists and industry partners who will develop key network components and quantum communication protocols that will facilitate in the long term the realization of large quantum computing clusters or even city-wide quantum networks using superconducting circuits.

The project is funded by the Horizon 2020 research and innovation programme of the European Union.

NEWS

A Quantum LAN at WMI

Researchers at the Walther-Meißner-Institut (WMI) have just reported on first demonstration experiments using their prototype superconducting QuLAN device (arXiv:2308.12398). Specifically, they have successfully distributed entangled microwave states across a ~6m long cryogenic link and found that the entanglement even survives when the link is heated up to temperatures of about 1 K. This finding will...

Autonomous entanglement distribution of multi-qubit entanglement

Theorists at TU Wien and the Walther-Meißner-Institut have proposed and analyzed a scheme for distributing multi-qubit entanglement in a robust and fully autonomous way.  In their scheme, qubits arranged along two optical or microwave waveguides are illuminated by correlated photons from a common two-mode squeezing source. The researcher showed that this basic process drives the...

Bell nonlocality in a superconducting quantum link

The experimental team at ETH Zürich has implemented a loophole-free test of Bell’s inequality in a superconducting setup. To achieve this breakthrough, the researchers created pairs of entangled qubits across a 30m long superconducting quantum link. In this way, any mutual influence of the measurements performed on both sides of the link could be ruled...

Scalable control scheme for multi-mode unitary transformations

Together with a partner from Sun Yat-sen University in China, CSIC and TU WIEN have proposed a new control scheme for implementing arbitrary lineart transformations between multi-mode bosonic quantum registers.  This is particullarly relevant for scaling-up quantum networks. The study has now been published in Physical Review Letters and a preprint can be found here:...

How to verify a quantum network?

Apart from building quantum computers in the first place, another nontrivial challenge is to verify that these computers then operate as expected. The theory group at MPQ has now proposed a protocol for performing such a verification step also for individual nodes of a quantum network and implement basic versions of these schemes on quantum...

Breakthrough in quantum network technology

Researchers at IST Austria have demonstrated for the first time the deterministic generation of entanglement between optical and microwave photons (arXiv:2301.03315). Together with their colleagues from TU Wien, they have verified quantum correlations between microwave photons inside a diluation refigerator and propagating optical photons. This is a first key step toward building scalable quantum networks...

Workshop & Summer School

Workshop & Summer School After two years of travel restrictions we are happy to announce that both our workshop on superconducting quantum networks as well as our summer school can take place in person in Sep. 2022. Please check Events for further updates...

Quantum eigenstate broadcasting assisted by a coherent link

In a collaboration with MPQ, J. Tura at aQa could show how a coherent link between two parties A and B can assist in finding the ground state or other eigenstates of complex Hamiltonians. A benefit is already obtained for a minimal amount of entanglement that is shared between the parties via the link. Overall...

Long-distance qubit-qubit entanglement using Gaussian photonic beams

TU Wien and IST have analyzed the distribution of entanglement over long distances by driving separated quantum nodes with the output of a two-mode squeezed parametric amplifier. This scheme is very robust with respect to various imperfections and is ideally suited for microwave-to-optics entanglement generation using the electro-optical device implemented at IST. Read more details...

Deterministic quantum operations in microwave quantum links

Deterministic quantum operations in microwave quantum links The theory teams in Madrid and Vienna have proposed and analyzed a set of deterministic quantum operations for implementing gates between remote qubits in a cryogenic quantum link, similar to the device implemented at ETH Zürich. Take a look at the preprint at: arXiv:2110.02092...

Photonic tensor network states in circuit QED

Photonic tensor network states in circuit QED Our partners at MPQ have described an efficient protocol to generate photonic tensor network states using superconducting quantum circuits. Read more details about this scheme in the preprint: arXiv:2109.06781...

Quantum interface between microwave and telecom light

Quantum interface between microwave and telecom light The group of Johannes Fink at IST Austria has demonstrated a pulse electro-optical transducer between microwave and telecom photons (arXiv:2107.08303). The impressively low amount of added noise (less than a single photon) is a big step forward toward our goal of realizing quantum-coherent interfaces between superconducting quantum processors...