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Photonic systems

Learn about photonic systems.

In an earlier Step, we visited the laboratory of Professor Akira Furusawa at the University of Tokyo, and learned about using photons as qubits. In this video, we continue that visit and learn more about how those experiments are conducted.

To build an optical quantum computer, we must have a source of single photons, and the ability to execute some of the gates we discussed in the second week. Those gates are performed using beam splitters and devices that change the phase of a photon. To create a complete set of gates, we need a nonlinear operation and the ability to measure the photons. Professor Furusawa shows us his setup for these operations.

Of course, the setup on a lab bench is too big to build a large system, so Professor Furusawa also shows us a chip, made out of silicon, that performs the same functions as an entire table top full of mirrors and beamsplitters. It uses wave guides, like the optical fiber that brings the Internet to your house. Rather than having many, many chips, instead the light is recirculated back through the chip, in a loop, until the process is complete.

silicon waveguide chip from Professor Furusawa's laboratory

Professor Furusawa ends by saying that the most important challenge for building an optical quantum computer is quantum error correction. We will discuss QEC in the next Activity.





silicon waveguide chip from Professor Furusawa's laboratory


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Understanding Quantum Computers

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