A new study has revealed that the proximity of dielectric and semiconductor materials can induce significant energy losses in superconducting qubits, affecting their coherence. This finding is crucial for the development of quantum computing, as decoherence is one of the biggest obstacles to building reliable and scalable quantum computers. The research details how interaction with these materials can generate two-level states (TLS) that act as energy sinks.

Superconducting qubits are promising due to their scalability and relatively long coherence times, but their performance is limited by interaction with the environment. Until now, attention had primarily focused on intrinsic losses of the superconducting material or at interfaces. This work expands understanding by demonstrating that adjacent materials, even if not an active part of the qubit, can be a dominant source of decoherence. Experiments were conducted by varying the distance between qubits and different types of materials, measuring how this affected relaxation and coherence times.

The results show that dielectric and semiconductor materials, such as silicon oxide or silicon, can drastically reduce qubit coherence times. A clear distance dependence was observed, suggesting that the qubit's electromagnetic field interacts with excitations in these materials. This interaction induces TLS, which absorb energy from the qubit, shortening its lifespan. Identifying these loss mechanisms is a fundamental step towards designing more robust qubits.

This discovery has direct implications for the design of future quantum processors. Engineers will now need to consider not only the quality of the qubit material but also the composition and spacing of surrounding materials on the chip. Mitigating these losses could be achieved by using materials with a lower density of TLS or by a design that minimizes qubit exposure to nearby fields. This paves the way for qubits with longer coherence times, an indispensable requirement for fault-tolerant quantum computing.