Quantum computing with
There are three major ways to build quantum computing hardware. Google and IBM use the superconducting qubit technology, where Josephson junction works as the foundation of engineered, macro-scale quantum bit (qubit). Another popular approach is ion trap, where energy sub-levels of atoms serve as qubit. The last approach is called linear optics quantum computing (LOQC), which is the subject of our research group.
Among different these approaches for quantum computing, integrated photonics stands out in its large-scale manufacturability. This manufacturing scalability is what promises the ultimate goal of quantum computing: fault-taulerant, error-corrected machine. However, LOQC is approach has the major challenge - it does not even have a single reliable qubit yet due to its non-deterministic nature.
The path to overcome this challenge has been laid out already. By multiplexing non-deterministic components, it is possible to make nearly-deterministic component. This scheme requires integration of many components: probabilistic single photons sources, single-photon detector, fast electronic circuit and optical switch. With the recent progress in the manufacturing capability of integrated photonic circuit and electronics, this goal seems to be within reach.
Based on this idea, our group works on producing single-photons by using nonlinear optical interaction in integrated photonics platform. For example, strong laser pulses can produce quantum photon pairs via nonlinear optical phenomena such as spontaneous parametric downconversion (SPDC) or spontaneous four-wave mixing (SFWM). With proper engineering of photonic circuit, it would be possible to obtain pure and efficient single photons which are good enough to be used in photonic quantum computation.