Hong–Ou–Mandel (HOM) interference is one of the most prominent features of quantum indistinguishable particles, and has been used as the core of many quantum information protocols1. Since its first observation in 19872, it has been understood as a phenomenon that occurs when two identical bosons are fed to two input ports of a beam splitter. Here, we report the observation of HOM interference exhibited by two photons with different colours3. We developed a frequency-domain beam splitter via a second-order nonlinear medium driven by strong coherent light4, 5. A photon passing through the device changes its colour probabilistically. When a single pulse containing two photons with different colours was fed to the beam splitter, the pair of output photons showed a tendency to assume the same colour, with a visibility exceeding the classical limit. Combined with wavelength-division multiplexing, our results will pave the way towards the miniaturization of highly integrated optical circuits for quantum information processing.
At a glance
- Multiphoton entanglement and interferometry. Rev. Mod. Phys. 84, 777–838 (2012). et al.
- Measurement of subpicosecond time intervals between two photons by interference. Phys. Rev. Lett. 59, 2044–2046 (1987). , &
- Interference of two photons of different color. Opt. Commun. 283, 747–752 (2010). , , &
- Frequency hopping in quantum interferometry: efficient up-down conversion for qubits and ebits. Phys. Rev. Lett. 90, 027902 (2003). , &
- Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon level. Opt. Express 21, 27865–27872 (2013). et al.
- Linear optical quantum computing with photonic qubits. Rev. Mod. Phys. 79, 135–174 (2007). et al.
- Demonstration of blind quantum computing. Science 335, 303–308 (2012). et al.
- Experimental validation of photonic boson sampling. Nature Photon. 8, 615–620 (2014). et al.
- Universal linear optics. Science 349, 711–716 (2015). et al.
- Measurement-device-independent quantum key distribution over 200 km. Phys. Rev. Lett. 113, 190501 (2014). et al.
- Experimental passive round-robin differential phase-shift quantum key distribution. Phys. Rev. Lett. 114, 180502 (2015). et al.
- Quantum repeaters based on atomic ensembles and linear optics. Rev. Mod. Phys. 83, 33–80 (2011). , , &
- Heralded entanglement between widely separated atoms. Science 337, 72–75 (2012). et al.
- Quantum teleportation between remote atomic-ensemble quantum memories. Proc Natl Acad. Sci. USA 109, 20347–20351 (2012). et al.
- Variations on the theme of quantum optical coherence tomography: a review. Quantum Inf. Process. 11, 903–923 (2012). , , &
- Indistinguishable photons from a single-photon device. Nature 419, 594–597 (2002). , , , &
- Two-photon interference of the emission from electrically tunable remote quantum dots. Nature Photon. 4, 632–635 (2010). et al.
- Quantum interference between two single photons emitted by independently trapped atoms. Nature 440, 779–782 (2006). et al.
- Quantum interference of photon pairs from two remote trapped atomic ions. Nature Phys. 3, 538–541 (2007). et al.
- Quantum interference of single photons from remote nitrogen-vacancy centers in diamond. Phys. Rev. Lett. 108, 143601 (2012). et al.
- Indistinguishable photons from separated silicon-vacancy centers in diamond. Phys. Rev. Lett. 113, 113602 (2014). et al.
- Observation of quantum interference in the plasmonic Hong–Ou–Mandel effect. Phys. Rev. Appl. 1, 034004 (2014). et al.
- Two-plasmon quantum interference. Nature Photon. 8, 317–320 (2014). , , &
- Atomic Hong–Ou–Mandel experiment. Nature 520, 66–68 (2015). et al.
- Hong–Ou–Mandel interference of two phonons in trapped ions. Nature 527, 74–77 (2015). , , &
- Observation of quantum beating in a simple beam-splitting experiment: Two-particle entanglement in spin and space-time. Phys. Rev. A 50, 2564 (1994). &
- Discrete tunable color entanglement. Phys. Rev. Lett. 103, 253601 (2009). &
- A photonic quantum information interface. Nature 437, 116–120 (2005). et al.
- Wide-band quantum interface for visible-to-telecommunication wavelength conversion. Nature Commun. 2, 537 (2011). et al.
- High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectors. Phys. Rev. A 87, 010301(R) (2013). et al.
- Quantum frequency conversion. Opt. Lett. 15, 1476–1478 (1990).
- Non-classical interference between independent sources. J. Opt. B 7, S171 (2005). , &
- Nonclassical two-photon interference between independent telecommunication light pulses converted by difference-frequency generation. Phys. Rev. A 88, 042317 (2013). et al.
- High performance fiber-coupled NbTiN superconducting nanowire single photon detectors with Gifford-McMahon cryocooler. Opt. Express 21, 10208–10214 (2013). , , &
- Supplementary information (475 KB)