Caltech develops efficient transducer for quantum computing advancements

Researchers are making progress in building superconducting quantum computers. These computers use microwave photons, which are small particles of microwave radiation, as qubits. Qubits are the essential components of quantum computing. Current microwave qubits are beneficial because they can be easily controlled and made at scale. However, these qubits need to be kept very cold, around 30 milliKelvin, to minimize background noise. This cold environment helps detect individual microwave photons. At warmer temperatures, these photons lose their quantum information too quickly to be useful. To send these microwave qubits over existing optical cables, similar to those used in the internet, they must first be converted into optical photons, which are higher energy particles. A new device developed by a team led by Mohammad Mirhosseini at Caltech can make this conversion more efficient. The Caltech device uses a vibrating silicon beam that interacts with a microwave resonator. This technology allows a microwave photon to be transformed into a mechanical vibration, which is then converted into an optical photon with the help of laser light. This process helps connect microwave and optical systems. Researchers have been focused on reducing noise during this conversion process. The Caltech team’s design, made from silicon, shows very little heating when exposed to laser light, which helps keep noise levels low. The new transducer is also highly efficient, converting microwave photons to optical photons about 100 times better than previous methods while maintaining low noise. This innovative approach has the potential to simplify the fabrication of quantum devices. The Caltech team is optimistic about demonstrating new capabilities that were previously difficult to achieve.