From quantum pulse gate to quantum pulse shaper—engineered frequency conversion in nonlinear optical waveguides

Abstract

Full control over the spatio-temporal structure of quantum states of light is an important goal in quantum optics, to generate for instance singlemode quantum pulses or to encode information on multiple modes, enhancing channel capacities. Quantum light pulses feature an inherent, rich spectral broadband-mode structure. In recent years, exploring the use of integrated optics as well as source-engineering has led to a deep understanding of the pulse-mode structure of guided quantum states of light. In addition, several groups have started to investigate the manipulation of quantum states by means of singlephoton frequency conversion. In this paper we explore new routes towards complete control of the inherent pulse-modes of ultrafast pulsed quantum states by employing specifically designed nonlinear waveguides with adapted dispersion properties. Starting from our recently proposed quantum pulse gate (QPG) we further generalize the concept of spatio-spectral engineering for arbitrary χ (2)based quantum processes. We analyse the sum-frequency generation based QPG and introduce the difference-frequency generation based quantum pulse shaper (QPS). Together, these versatile and robust integrated optics devices allow for arbitrary manipulations of the pulse-mode structure of ultrafast pulsed quantum states. The QPG can be utilized to select an arbitrary pulse mode from a multimode input state, whereas the QPS enables the generation of specific pulse modes from an input wavepacket with Gaussian-shaped spectrum.

Electro-Optic Frequency Beam Splitters and Tritters for High-Fidelity Photonic Quantum Information Processing

“…Important examples include the quantum pulse gate [2,3], which uses nonlinear mixing with shaped classical pulses for selective conversion of the time-frequency modes of single photons [4][5][6], and demonstrations of frequency beamsplitters based on both χ (2) [7,8] and χ (3) [9][10][11] nonlinearities, which interfere two wavelength modes analogously to a spatial beamsplitter. These seminal experiments have shown key primitives in frequency-based QIP, but many challenges remain.…”

Quantum-state-preserving optical frequency conversion and pulse reshaping by four-wave mixing

“…(At the photon level, π s ←→ π p + π r , where π j represents a photon with carrier frequency ω j .) Recently, it was shown theoretically that TWM, in conjunction with spectral phase modulation and propagation [11], or dispersion engineering [12], can connect pulses with disparate durations (quasicontinuous waves are converted to short pulses, or vice versa). However, TWM is limited in practice to large frequency shifts, which prevents its use for FC within the telecommunication bands.…”

Multidimensional quantum information based on single-photon temporal wavepackets

“…Nevertheless, in these Franson-type unbalanced-interferometer approaches the dimension of the Hilbert space is not flexible because of discrete time bins determined once and for all by the structure of the interferometers [12,13]. There have been recent proposals to use ultrafast nonlinear optical processes for projections onto continuous modes [14][15][16][17]. However, such broadband frequency-based approaches are impossible to implement in fiberoptical realizations due to the strong dispersion and nonlinearities in fibers.…”