Intrinsic Photon Loss at the Interface of Superconducting Devices

Area of Science:

• Quantum physics
• Condensed matter physics
• Materials science

Background:

• Superconducting devices are crucial for quantum computing.
• Dielectric energy loss is a major limitation for superconducting qubit performance.
• Existing theories often attribute loss to defects like two-level systems.

Purpose of the Study:

• To present a quantum theory for dielectric energy loss in superconducting devices.
• To identify the primary mechanism and location of photon loss.
• To quantify the potential impact on superconducting qubit coherence times.

Main Methods:

• Developed a quantum theory based on piezoelectric coupling between photons and phonons.
• Analyzed loss mechanisms at material interfaces.
• Performed explicit numerical calculations of the intrinsic loss tangent.

Main Results:

• Photon loss predominantly occurs at interfaces due to piezoelectric coupling.
• This loss mechanism is present even in defect-free, crystalline (epitaxial) materials.
• Calculated intrinsic loss tangents for several interfaces.

Conclusions:

• The piezoelectric effect at interfaces is a significant source of dielectric loss.
• Achieving defect-free interfaces could lead to vastly improved superconducting qubit lifetimes (T1 > 10,000 μs).
• This work provides a pathway for designing more robust superconducting quantum devices.