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Institute of Industrial Science
Institute for Nano Quantum Information Electronics
Arakawa-Arita-Ota lab
Iwamoto lab

RESEARCH FUNDING


Research outline

I have been investigating the optical properties of a wide range of material nanostructures, including III-V materials (InGaAs/GaAs, InGaN/GaN/AlGaN), II-VI materials (ZnO, ZnSe etc), and group IV materials (carbon nanotubes). Recently I have been focussing on III-nitride nanostructures for the development of future optoelectronic devices. III-nitrides are fast becoming one of the most important materials used in the optoelectronics industry, and are currently finding commercial application in "classical" devices such as LEDs, laser diodes, and power electronics. The Holmes lab is situated at the frontier of III-nitride materials research, and we are now investigating if these fascinating materials can be used for the development of quantum technologies.

In particular we are studying semiconductor nanostructures known as quantum dots (sometimes referred to as artificial atoms), which are able to confine individual electrons in a region of space of a few nanometers in size, and hence are able to generate single photons of light. Such single photon emitters will be useful for future quantum technologies including quantum cryptography/communication and optical quantum computing. Typically, experiments using semiconductor quantum dots are performed using costly and cumbersome cryogenic cooling systems to reduce the material temperature to around 4K (-269C, -452F). However, we have shown that III-nitride quantum dots can be used to realize single photons of light at temperatures up to room temperature and beyond (at temperatures even hot enough to boil an egg!). These studies provide hope that such structures can be used for future quantum information processing applications in hot environments such as inside data centers, without the need for the aforementioned cooling systems.

Moreover, we have shown that it is possible to generate single photons with high purity (g(2)(0)<0.02) using III-nitride quantum dots at low temperature, and have also been developing several theoretical models to explain the physical processes that determine the emission properties.

Our current themes of research involve studies on the excitation and recombination dynamics of III-nitride quantum dots, and additionally the development of photonic structures to increase the device efficiency.

We recently published an open access invited review paper on the topic, which can be downloaded and enjoyed for free here.


Measurement systems

Our typical method of experiment is to use microphotoluminescence spectroscopy, which allows us to probe the emision properties of various materials/nanostructures via excitation with high energy lasers. The images in the slideshow below show parts of our advanced PL setup that we have developed and use for probing the carrier dynamics and other properties of various nanostructures. Experiments are can be performed at temperatures ranging from 4K to 400K, using a variety of wavelengths.