Research Subjects
| Quantum transport | We study quantum transport phenomena in quantum dots, quantum wells and atomic layer materials. These quantum phenomena realized on the confined electron systems have potential as the generation and detection of terahertz light. We explore the interplay between electron systems and the other quantum systems such as photon, phonon and spin systems. |
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| THz photon detection | We are developing THz single photon detectors using semiconductor quantum structures. Recently, we focus on charge sensitive infrared phototransistors using a GaAs/AlGaAs multiple quantum well structure . Based on this detection scheme, we aim to realize a single photon detector in the mid-infrared region.
D. Nakagawa et al., Jpn. J. Appl. Phys. 57, 04FK04 (2018).
Charge sensitive infrared phototransistor (CSIP) |
| THz photon emission | When a strong magnetic field is applied to a two-dimensional electron system, electrons occupy orbits with discrete energy values (Landau levels). Under such circumstances, it often happens that the Hall resistance is quantized and the longitudinal resistance becomes zero (quantum Hall effect). We study the inter-Landau-level optical transition in the current-injected quantum Hall devices.
F. Inamura et al., APL Photonics 9, 116101 (2024).
K. Ikushima et al., Phys. Rev. B 84, 155313 (2011).
Laundau-level emission from graphene (right). Landau-level emission from quantum Hall edge channels (left) |
THz Manipulation | THz single photon detectors and THz photon sources are integrated on a single chip to study the interplay between quantum electron transport and quantum optics.
K. Ikushima et al., Appl. Phys. Lett. 104, 052112 (2014).
Generation, transmission and detection of THz photons on an electrically driven single chip |
| THz Microscopy | We are developing a microscope equipped with an ultra-highly sensitive THz detector fabricated in the Lab. This microscope revealed the spatial distribution of cyclotron emission in a two-dimensional electron system, and made it possible to understand nonequilibrium carrier dynamics in quantum Hall effect conductors. In the future, we would like to use it not only for studies of semiconductor devices, but also for studies of atomic layers or new materials.
K. Ikushima and S. Komiyama, C. R. Physique 11, 444 (2010).
K. Ikushima et al., Phys. Rev. B 76, 165323 (2007).
K. Ikushima et al., Appl. Phys. Lett. 88, 152110 (2006).
K. Ikushima et al., Phys. Rev. Lett. 93, 146804 (2004).
K. Ikushima et al., Rev. Sci. Instrum. 74, 4209 (2003).
Cyclotron emission imaging of quantum Hall effect devices |