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Few-hole double quantum dot in an undoped GaAs/AlGaAs heterostructure

Applied Physics Letters

Tracy, L.A.; Hargett, Terry H.; Reno, J.L.

We demonstrate a hole double quantum dot in an undoped GaAs/AlGaAs heterostructure. The interdot coupling can be tuned over a wide range, from formation of a large single dot to two well-isolated quantum dots. Using charge sensing, we show the ability to completely empty the dot of holes and control the charge occupation in the few-hole regime. The device should allow for control of individual hole spins in single and double quantum dots in GaAs. © 2014 AIP Publishing LLC.

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TYPE Journal Article YEAR 2014
ScopusOSTI

Terahertz near-field probe incorporating a λ/100 aperture for time-domain spectroscopy and imaging

Proceedings of SPIE - The International Society for Optical Engineering

Macfaden, Alexander J.; Reno, J.L.; Brener, Igal B.; Mitrofanov, Oleg

Achieving high spatial resolutions for imaging with terahertz (THz) waves requires near-field probes, such as a sub-wavelength aperture probe. Bethe's theory of transmission through a sub-wavelength aperture of size a predicts that the transmitted electric field scales as Eαa3. This strong dependence limits the size of apertures that can be employed and hence the spatial resolution. This dependence however changes for the evanescent field components in very close proximity (∼1μm for THz waves) to the aperture, as shown by electromagnetic simulations. To exploit this effect in a THz near-field probe, we developed a photoconductive THz near-field detector structure, which incorporates a thinned photo-conductive detector region and a distributed Bragg reflector between the detector and the aperture plane. Near-field probes are manufactured with different aperture sizes to investigate transmission of THz pulses through apertures as small as 3μm. The experimental results confirm that the transmitted field amplitude, and therefore the sensitivity, increases by about one order of magnitude for the new probes. A 3μm aperture probe with a spatial resolution of λ/100 at 1THz is demonstrated.. © 2014 SPIE.

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TYPE Conference YEAR 2014
ScopusOSTI

Transmission of THz pulses through 3μm apertures: Applications for near-field microscopy

Optics InfoBase Conference Papers

Macfaden, Alexander J.; Reno, J.L.; Brener, Igal B.; Mitrofanov, Oleg

We demonstrate that THz pulses transmitted through small apertures (~λ/100) exhibit strong evanescent components within 1μm of the aperture. Using this effect, we developed subwavelength aperture THz near-field probes that provide 3μm resolution. © 2014 OSA.

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TYPE Conference YEAR 2014
ScopusOSTI
Results 151–175 of 343
Results 151–175 of 343