A proposal of multistage quantum pulse gate for a wavelength-division-multiplexed quantum simulator

• Published in: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) p. 1
• Main Authors: Hosaka, Aruto, Otsuka, Tsubasa, Tomita, Masaya, Kannari, Fumihiko
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-06-2017
• Subjects: Nonlinear optics; Optical pulse shaping; Optical waveguides; Photonics; Quantum computing; Time-frequency analysis
• DOI: 10.1109/CLEOE-EQEC.2017.8087378

Summary form only given. Optical linear circuit is one of the most important parts for optical quantum computing. The optical circuit, which consists of mode mixers and phase shifters, has been used in various quantum protocols: cluster state generation, Boson sampling, and quantum random walk. To realize a large-scale linear circuit, waveguide-based quantum circuits have experimentally been demonstrated by some groups [1, 2]. However, such a waveguide-based circuit cannot overcome issues of flexibility and loss.On the other hand, recently, a quantum pulse gate (QPG), which enables mode extraction from multimode quantum fields in the frequency domain, has been proposed and experimentally demonstrated [3]. For utilizing the frequency resource of photon field, parallel generations of single photons or multimode squeezed states in the frequency domain, namely time-frequency Schmidt modes, have been demonstrated. In such a wavelengthdivision-multiplexed quantum circuit, this mode extraction corresponds to one row of a linear unitary rotation of the Schmidt modes. It is achieved by sum frequency generation between a spectrally-shaped classical pulse and a quantum weak pulse. The arbitrary mode extraction can be designed by the pulse shaping with a high efficiency. In this report, we propose a multistage QPG which is a simple, flexible and highly efficient quantum linear optical circuit. We devised a novel multipass 4-f system to map the frequency multimode quantum states into the spatiotemporal domain with a single nonlinear crystal (Fig. 1(a)). Furthermore, we show its application to a quantum simulator for calculating molecular vibronic absorption spectra [4] (Fig. 1(b)).