• Speaker: Dr. Kim, Hyochul (Samsung Advanced Institute of Technology)
  • Date: April 11, 2017
  • Place: Science Building 433


Abstract

The ability to interface light with solid-state quantum bits (qubits) is essential for future development of scalable and compact quantum information systems that operate on ultra-fast timescales. Photons act as ideal carriers of quantum information and can serve as an efficient quantum link between matter qubits. Quantum dots (QDs) provide a promising implementation of a matter qubit, which can store quantum information in both excitonic states and highly stable spin states, providing an atom-like system in a semiconductor platform. By coupling these QDs to optical nano-cavities it becomes possible to achieve the strong coupling regime where a QD can modify the cavity spectral response, providing an efficient light-matter interface. In this talk, I will explain that the qubit state of a photon can be controlled by a single solid-state qubit composed of an InAs QD strongly coupled to a photonic crystal cavity. The QD acts as a coherently controllable qubit system that conditionally flips the polarization of a photon reflected from the cavity on picosecond timescales, which implements a controlled NOT logic gate between the QD and the incident photon. Furthermore, the spin of a single electron or hole trapped in a charged QD can be used as a solid-state qubit with long coherence time. I will discuss our recent experimental realization of a quantum phase switch using a solid-state spin confined in a QD strongly coupled to a photonic crystal cavity, where the switch applies a spin-dependent phase shift on a photon. In addition, I will introduce some of research works at Samsung Advanced Institute of Technology (SAIT), focusing on novel photonic devices using colloidal quantum dots (CQDs). I will explain our demonstration of CQD LEDs and lasers as well as emission control of CQD LEDs with nano-antenna structures­­­.


References

  1. Hyochul Kim, Ranojoy Bose, Thomas C. Shen, Glenn S. Solomon, and Edo Waks, A quantum logic gate between a solid-state quantum bit and a photon, Nature Photonics, 7, 373 (2013)
  2. Shuo Sun, Hyochul Kim, Glenn S. Solomon and Edo Waks, A quantum phase switch between a single solid-state spin and a photon, Nature Nanotechnology, 11, 539 (2016)
  3. Hyochul Kim, Kyung-Sang Cho, Heejeong Jeong, Jineun Kim, Chang-Won Lee, Weon-Kyu Koh, Young-Geun Roh, Sungwoo Hwang, Yeonsang Park, Single-mode lasing from a monolithic microcavity with few-monolayer-thick quantum dot films, ACS Photonics, 3, 1536 (2016)