Innolum ESR

Lasers, sources of single photons and entangled photon pairs based on “quantum dot in nanowire system"

Innolume GmbH

Long-distance quantum communication is one of the prime goals in the field of quantum information and with information encoded in the quantum state of photons, existing telecommunication fibre networks can be effectively used as a transport medium for routing photonic qubits, make quantum correlations and entanglement between different nodes. Quantum networks can interconnect remote quantum processors, and links between different architectures to increase net computational power.

Polarization entangled photons suffer from decoherence in optical fibers due to polarization mode dispersion. This effect results in the wavelength and time-dependent splitting of the principal states of polarization with a differential group delay. Thus, the arrival time of the photons carries information about their polarization state causing decoherence.

So, to achieve Long-distance quantum communication, a source of coherent entangled single-photon pairs is required and quantum dots embedded in nanowire waveguides with a controlled shape could serve as an efficient source of single photons and entangled photon pairs for use in quantum cryptography and quantum computing. Quantum information protocols such as quantum teleportation and entanglement swapping use entangled photons to enable long-distance distribution of entanglement through quantum repeaters.

Our goal is to develop and design a prototype of a laser using quantum dots embedded in nanowire waveguides of which the emitted photons would be anti-bunched and violate Bell’s inequality by at least 5 standard deviations. The first step would be growing site-controlled quantum dots in tapered nanowire waveguide, one candidate would be the InP nanowires containing single InAsP quantum dots. The second step would be to implement them as integrated devices. The last step is to grow them in industrially reliable scale, this would be very challenging because although advanced devices based on nanowires (NWs) are drawing much attention, devices based on a single NW are not suitable for general manufacturing purposes, as it is still extremely difficult to control the electronic properties, growth and alignment of individual NWs on an industrially reliable scale. Nevertheless we would try to go one big step farther toward this goal.