Quantum Optics Seminar by Prof. Akira Furusawa

Optical quantum computers with quantum teleportation

We did the first experiment of unconditional quantum teleportation at Caltech in 1998 [1]. Then we did various related experiments like quantum teleportation network [2], teleportation of Schrödinger’s cat state [3], and deterministic quantum teleportation of photonic qubits [4].
We invented the scheme of teleportation-based quantum computing in 2013 [5]. In this scheme, we can multiplex quantum information in the time domain and we can build a large-scale optical quantum computer only with four squeezers, five beam splitters, and two optical delay lines [6].
For universal quantum computing with this scheme, we need a nonlinear measurement and we invented the efficient way [7]. We recently succeeded in the realization [8].
Our present goal is to build a super quantum computer with 100GHz clock frequency and hundred cores, which can solve any problems faster than conventional computers without efficient quantum algorithms like Shor’s algorithm. Toward this goal we started to combine our optical quantum computer with 5G technologies [9].

1. A. Furusawa et al., Science 282, 706 (1998).
2. H. Yonezawa et al., Nature 431, 430 (2004).
3. N. Lee et al., Science 332, 330 (2011).
4. S. Takeda et al., Nature 500, 315 (2013).
5. S. Yokoyama et al., Nature Photonics 7, 982 (2013).
6. W. Asavanant et al., Science 366, 375 (2019).
7. K. Miyata et al., Phys. Rev. A 93, 022301 (2016).
8. A. Sakaguchi et al., arXiv:2210.17120 [quant-ph].
9. A. Inoue et al., arXiv:2205.14061 [quant-ph]

Department of Applied Physics, School of Engineering, The University of Tokyo