Spectral compression of single photons

Abstract

Photons are critical to quantum technologies since they can be used for virtually all quantum information tasks: in quantum metrology, as the information carrier in photonic quantum computation, as a mediator in hybrid systems, and to establish long distance networks. The physical characteristics of photons in these applications differ drastically; spectral bandwidths span 12 orders of magnitude from 50 THz for quantum-optical coherence tomography to 50 Hz for certain quantum memories. Combining these technologies requires coherent interfaces that reversibly map centre frequencies and bandwidths of photons to avoid excessive loss. Here we demonstrate bandwidth compression of single photons by a factor 40 and tunability over a range 70 times that bandwidth via sum-frequency generation with chirped laser pulses. This constitutes a time-to-frequency interface for light capable of converting time-bin to colour entanglement and enables ultrafast timing measurements. It is a step toward arbitrary waveform generation for single and entangled photons.Comment: 6 pages (4 figures) + 6 pages (3 figures

Large-alphabet time-frequency entangled quantum key distribution by means of time-to-frequency conversion

“…As mentioned previously, the large timing jitter ( 200 ps for APDs) of efficient photon-counting detectors makes it challenging to resolve the temporal correlations directly. Instead, we propose to implement measurements in the time basis by sending each photon through a time-to-frequency converter [47,48,49]. As shown in Fig.…”

Quantum temporal imaging: application of a time lens to quantum optics

“…Quantum temporal imaging can borrow many ideas and techniques from its spatial counterpart. Several approaches to the quantum temporal imaging at the single-photon level have been published in the last decade [24,25,26,27], but the case of continuous variables has been considered only recently [28]. It has been shown that having a squeezed light as the object imposes additional constraints on the temporal imaging system, if one aims at preserving the quantum structure of the object, namely, its degree of squeezing.…”

Temporal and spectral manipulations of correlated photons using a time lens

“…This characteristic feature has led to the development of a variety of techniques for spectral and temporal manipulations of single photons [5][6][7][8][9][10][11][12]. Recently, spectral compression of photons has gained widespread attention in order to efficiently interface wide-band sources of correlated photons with narrow-band nodes of a quantum network, for example, quantum dots and atomic systems [11,[13][14][15]. At the same time, temporal magnification of photons facilitates high-fidelity photonic measurements in quantum simulations [16][17][18][19].…”