Generation and Characterization of Multimode Quantum Frequency Combs

Abstract

Multimode nonclassical states of light are an essential resource in quantum computation with continuous variables, for example in cluster state computation. We report in this paper the first experimental evidence of a multimode non-classical frequency comb in a femtosecond synchronously pumped optical parametric oscillator. In addition to a global reduction of its quantum intensity fluctuations, the system features quantum correlations between different parts of its frequency spectrum. This allows us to show that the frequency comb is composed of several uncorrelated eigenmodes having specific spectral shapes, two of them at least being squeezed, and to characterize their spectral shapes.PACS numbers: 42.50. Dv, 42.50.Lc, 42.65.Yj Optical frequency combs are perfect tools for high precision metrological applications [1,2]. The extension of their extraordinary properties to the quantum domain may lead to significant progress in different areas of quantum physics, in particular in quantum metrology and parameter estimation [3,4], but also in quantum computation with continuous variables [5,6]. Indeed, one of the main challenges of experimentally implementing quantum computers in the continuous variable regime, for example in cluster state computation [6,7], is the generation of highly multimode non-classical states of light, and the scalability of this generation. As the difficulty of linearly mixing distinct squeezed light sources [8,9] increases as the number of modes increases, it can be more interesting to use instead a single highly multimode source which directly produces non-classical resources shared between many modes within a same beam. In this perspective, optical frequency combs, which span over thousands of different frequency modes, are a very promising system for scalable generation of spectral/temporal multimode quantum states. We report in this paper the first experimental evidence of multimode non-classical frequency comb generated by an Optical Parametric Oscillator (OPO) in the femtosecond regime, which opens the way to the generation of these highly multimode states.Multimode non-classical light has been already experimentally generated with spatial multimode beams produced by OPOs [10,11], and very recently, with the longitudinal modes of an OPO [12,13]. In the domain of temporal modes, single mode squeezing of short pulses has been observed in various experiments starting from [14] in the nanosecond regime. Non-classical states of single femtosecond pulses are the subject of many recent studies (for example [15]). Multimode squeezed solitons have been generated in an optical fiber [16]. Single mode quantum noise reduction in picosecond frequency combs has already been achieved with a Synchronously Pumped Optical Parametric Oscillator (SPOPO) [17], which is an OPO pumped by a train of ultrashort pulses that are synchronized with the pulses making round trips inside the optical cavity.It has recently been shown [18,19] that such SPOPOs generate squeezed frequency combs which are multimode. ...

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

“…Below threshold, they produce multimode squeezed states, which has been observed experimentally [42,45]. When operated above threshold, such multimode devices have been recently proved to be capable of producing non-critically squeezed states of light via the phenomena of spontaneous symmetry breaking [32,33,35,41,46] and pump clamping [37,42].…”

“…Hence (43) can be seen as the diagonal form of (45). For each choice of the coupling matrix K, which can be chosen as symmetric without loss of generality, this Hamiltonian generates a different type of multipartite entanglement between theB modes.…”

Multifrequency sources of quantum correlated photon pairs on-chip: a path toward integrated Quantum Frequency Combs

“…We note, however, that in the one-way quantum computing the complexity is shifted from the state control and manipulation to its generation: the different algorithms are realized simply through different measurements. In particular, recent developments in bulk optics [55][56][57][58][59][60], indicate that quantum frequency combs may represent a viable solution for one-way quantum computing. In light of this, our recent results on the generation of wavelength multiplexed photon pairs in microring resonators demonstrate that this is a venue that should be investigated in integrated platforms.…”

Noiseless signal shaping and cluster-state generation with a quantum memory cell

“…The duration of a single pulse in each train is T 0 , and the period between pulses is T . According to the experiment [26], the relation T 0 << L/c << T is met, so that at any given time not more than one pulse propagates through the medium. During the readout, the driving runs in the opposite direction, since we consider the case of a backward readout that is much more efficient than a forward one [27][28][29][30].…”