Entanglement—the defining quantum correlation between distant particles—is a key resource for quantum networks, but generating it typically requires carefully engineered coherent control and low-noise conditions. Thermal noise, the random fluctuations present in any warm environment, is usually considered the enemy; it destroys quantum coherence and prevents the formation of entangled states. In a new paper recently published in the journal Quantum, researchers at WMI proposed a protocol that turns this intuition on its head. They predicted that two distant qubits, connected by a quantum channel and driven by a filtered but purely thermal noise source, gradually relax into a highly entangled state. This process happens even without any coherent driving or active control and could, therefore, open up a new and resource-efficient route for scalable quantum information processing applications.
Together with Bluefors, we attached one of our quantum processors to a Bluefors LD dilution refrigerator this week at the DPG Spring Meeting in Dresden. The chip comprises 17 superconducting Transmon qubits integrated with 24 tunable coupling elements that precisely control the interactions between qubits. To protect the quantum states from thermal noise, we cool qubits to millikelvin temperatures. At the WMI, we are using these superconducting quantum processors to explore the fundamental limits of decoherence and to develop and improve scalable architectures. Events like the DPG spring meeting are always wonderful opportunities to engage with the broader condensed-matter physics community. We are happy that we were able to show one of our quantum processors together with Bluefors this year.
Matthias Opel hosted 9 physics teachers from the Michaeli-Gymnasium in Munich. They performed experiments at low temperatures with liquid nitrogen. Matthias explained the Meißner-Ochsenfeld effect and showed the levitation of a high-Tc (YBa2Cu3O7−δ) superconductor above a permanent magnet by demonstrating the superconducting WMI racetrack. Achim Marx and Matthias Opel then took them on a tour in the institute and showed the quantum physics and the spintronics labs. Finally, Matthias explained how magnetic fields influence the electrical resistivity of materials, known as "magnetoresistance effect".
The latest publication of the quantum computing group at WMI (published in Rev. Phys. Appl.) was featured in "Physics" as an editor's pick. Researchers at WMI have demonstrated that replacing aluminum with niobium for on-chip air bridges can significantly improve the robustness of superconducting quantum processors. Beyond their usual role in routing, the team integrated these air bridges directly as capacitive elements in superconducting qubits and achieved median coherence times of 51.6 µs. A promising step toward more resilient and scalable quantum devices!
This work was supported by Munich Quantum Valley, MUNIQC-SC, the Munich Center for Quantum Science and Technology, and the OpenSuperQPlus Flagship project.
The European Union has awarded €25 million to the SUPREME consortium. The project brings together 23 European companies and research organisations (including WMI) to fabricate and demonstrate a 3D-integrated quantum computer with 200 qubits.
Over the next 3.5 years, SUPREME will showcase improved stability, higher yield, and greater reproducibility in the key fabrication processes for superconducting quantum chips - an important step toward industrial-scale quantum technologies.
Read the full press release here.
We look forward to achieving this ambitious goal together with all our partners.
In an idle stage, quantum information stored in stationary qubits can be protected against ubiquitous low-frequency noise by periodically flipping the 0 and 1 states with a sequence of fast control pulses—a technique known as 'spin echo.' So far, however, such techniques have not been applicable while a qubit is coupled to a microwave or optical mode, which is necessary to mediate long-range gate operations and to implement quantum communication protocols. In an international collaboration with researchers from Bilbao, Paris, and ETH Zurich, the theory group at WMI has now developed a new control strategy that closes this gap and enables the protection of quantum states during their interaction with a photonic mode. This technique is completely general and can be applied to a wide range of quantum technological applications that rely on coherent interfaces between qubits and photons.
