A quantum internet promises completely secure communication. But using quantum bits or qubits to carry information requires a radically new piece of hardware—a quantum memory. This atomic-scale device needs to store quantum information and convert it into light to transmit across the network.
A major challenge to this vision is that qubits are extremely sensitive to their environment, even the vibrations of nearby atoms can disrupt their ability to remember information. So far, researchers have relied on extremely low temperatures to quiet vibrations but, achieving those temperatures for large-scale quantum networks is prohibitively expensive.
Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the University of Cambridge have developed a quantum memory solution that is as simple as tuning a guitar.
The researchers engineered diamond strings that can be tuned to quiet a qubit’s environment and improve memory from tens to several hundred nanoseconds, enough time to do many operations on a quantum chip.
“Impurities in diamond have emerged as promising nodes for quantum networks,” said Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior author of the research. “However, they are not perfect. Some kinds of impurities are really good at retaining information but have a hard time communicating, while others are really good communicators but suffer from memory loss. In this work, we took the latter kind and improved the memory by ten times.”
The research is published in Nature Communications.