In the late 1950s and ’60s, physicists observed unusual bumps in the peaks of the electromagnetic spectrum. These bumps were ephemeral, lasting only a billionth of a trillionth of a second, and they suggested the existence of particles that could be detected only through a process called resonance.
These ephemeral particles are now known as quarks and, thanks to quantum mechanics, can be measured much more rapidly than ever before, providing insights into areas such as astrophysics and medicine. They are also more resistant to noise, a critical factor in the development of quantum sensors and, ultimately, quantum networks and quantum communication.
A key component of these sensors is quantum frequency conversion (QFC), which links photons with different frequencies using light-matter interactions that are not affected by ultra-high noise. However, existing QFC techniques for linking the visible and telecom bands – including sum/difference frequency generation and four-wave mixing Bragg scattering – suffer from excessive broadband noise caused by the long wavelength pump laser(s).
To address this issue, researchers led by a team at NIST developed an on-chip low-noise quantum frequency converter that is based on three-mode upconversion/downconversion. It can be used to connect quantum dots that emit photons at different frequencies into fiber-based quantum memory systems, and is a step toward developing chip-scale devices for quantum information science.