Researchers at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS) have found a novel method to safeguard delicate quantum information using microscopic sound waves known as mechanical vibrations. This advancement could pave the way for efficient quantum networks integrated on chips and facilitate hybrid quantum systems combining different qubit types.
The research, led by Eliza Cornell and Zhujing Xu, is detailed in Nature Physics. A key aspect involves using the spin of electrons associated with diamond impurities to store quantum information, with tiny packets called phonons acting as carriers between qubit nodes. Phonons have advantages over light for quantum networking, including shorter wavelengths that allow for smaller, denser components and better interaction with solid-state spins.
One of the significant challenges in utilizing phonons is protecting quantum memory, as qubits are highly sensitive to environmental disturbances and require long coherence times for effective information storage. Traditional methods using microwave pulses are less effective in phononic cavities.
To tackle this, the research team developed an “all-mechanical coherence protection” method for a silicon-vacancy spin in diamond. By applying a continuous mechanical driving field made from phonons, they transformed the qubit into a “dressed” qubit, which is less susceptible to low-frequency noise. This technique can enhance coherence time and simultaneously stabilize the qubit within phononic cavities.
Overall, their innovative approach increased the coherence time of the silicon-vacancy spin by approximately three times, showing the potential for sound waves to play a crucial role in building more reliable quantum systems. The research was supported by various U.S. federal organizations and is under patent consideration for possible commercialization.
