Quantum optical synthesis of time-frequency entangled photons

Shigeki Sakuma, Hiroki Oshima, Tatsuya Hasegawa +3 more

Ryōsuke Shimizu

Rui‐Bo Jin, Hiroki Oshima, Takumi Yagisawa +5 more

Precise manipulation of the time–frequency modes of entangled photons is crucial for future quantum science and technologies. Recently, the frequency-domain-quantum-optical-synthesis (FD-QOS) method was demonstrated by creating a superposition of different joint temporal amplitudes: those temporal distributions can be controlled by manipulating the joint spectral amplitude in 2D frequency space via a Fourier optical relation. This FD-QOS method provides an efficient, flexible, and easy-to-control way to precisely modulate the temporal distributions of the entangled photon in an ultrafast region. However, manipulation of only the temporal modes is not sufficient for various applications in quantum information, since spectral modulations are also needed on many occasions. Here, we present a proof-of-concept experiment of two-photon spectral modulation via temporal manipulation of a biphoton wave packet. This protocol, called time-domain-quantum-optical-synthesis (TD-QOS), is achieved by adjusting the relative phases between two joint temporal distributions. In addition, the two-photon joint spectral distributions are characterized by measuring the joint spectral intensities and Hong–Ou–Mandel interferences. The combination of FD-QOS and TD-QOS enables complete control over the biphoton states. Our work would further develop quantum technologies that rely on the time–frequency modes of entangled photons.

Shigeki Takeuchi

Rui‐Bo Jin, Kurumi Tazawa, Naoto Asamura +6 more

Conventional optical synthesis, the manipulation of the phase and amplitude of spectral components to produce an optical pulse in different temporal modes, is revolutionizing ultrafast optical science and metrology. These technologies rely on the Fourier transform of light fields between time and frequency domains in one-dimensional space. However, within this treatment, it is impossible to incorporate the quantum correlation among photons. Here, we expand the Fourier synthesis into high-dimensional space to deal with the quantum correlation and carry out an experimental demonstration by manipulating the two-photon probability distribution of a biphoton in two-dimensional time and frequency space. As a potential application, we show the manipulation of a heralded single-photon wave packet, which is never explained by the conventional one-dimensional Fourier optics. Our approach opens up a new pathway to tailor the temporal characteristics of a photon wave packet with high-dimensional quantum-mechanical treatment. We anticipate that such high-dimensional treatment of light in time and frequency domains could bridge the research fields between quantum optics and ultrafast optical measurements.

Tomoya Okita, Yuta Fujihashi, Masahiro Yabuno +4 more

We present an alternative approach to creating frequency-bin states using Fourier optical synthesis with a nonlinear interferometer. The observed data demonstrate the control range of frequency spacing from 12.5 GHz to 3.2 THz.