Non-classical correlations between single photons and phonons from a mechanical oscillator

• Published in: Nature (London) Vol. 530; no. 7590; pp. 313 - 316
• Main Authors: Riedinger, Ralf, Hong, Sungkun, Norte, Richard A., Slater, Joshua A., Shang, Juying, Krause, Alexander G., Anant, Vikas, Aspelmeyer, Markus, Gröblacher, Simon
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.02.2016; Nature Publishing Group
• Subjects: 639/624/400/482; 639/766/400/3925; 639/766/400/482; 639/766/483; 639/766/483/1139; Analysis; Atoms & subatomic particles; Humanities and Social Sciences; Influence; letter; multidisciplinary; Oscillators (Electronics); Photons; Quantum physics; Quantum theory; Science; Transducers
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature16536

Non-classically correlated pairs of single photons and phonons are generated and read out from a nanomechanical resonator, demonstrating that such resonators could be used for light–matter quantum interfaces. A new quantum information architecture Most quantum communication, quantum storage and quantum transduction protocols require an optical interface to single mechanical quanta of motion — that is, to single photons and phonons. Here Simon Gröblacher and colleagues demonstrate a quantum interface between non-classically correlated pairs of single photons and phonons, generated and read-out from a nanomechanical resonator. This proof-of-principle experiment implies the practicality of on-chip solid-state mechanical resonators as light–matter quantum interfaces. Interfacing a single photon with another quantum system is a key capability in modern quantum information science. It allows quantum states of matter, such as spin states of atoms 1 , 2 , atomic ensembles 3 , 4 or solids 5 , to be prepared and manipulated by photon counting and, in particular, to be distributed over long distances. Such light–matter interfaces have become crucial to fundamental tests of quantum physics 6 and realizations of quantum networks 7 . Here we report non-classical correlations between single photons and phonons—the quanta of mechanical motion—from a nanomechanical resonator. We implement a full quantum protocol involving initialization of the resonator in its quantum ground state of motion and subsequent generation and read-out of correlated photon–phonon pairs. The observed violation of a Cauchy–Schwarz inequality is clear evidence for the non-classical nature of the mechanical state generated. Our results demonstrate the availability of on-chip solid-state mechanical resonators as light–matter quantum interfaces. The performance we achieved will enable studies of macroscopic quantum phenomena 8 as well as applications in quantum communication 9 , as quantum memories 10 and as quantum transducers 11 , 12 .