Talk given by

Dr. Vadim Khrapai
Institute of Solid State Physics of the Russian Academy of Sciences
Chernogolovka, Russia

Abstract:

Spontaneous fluctuations of the electric current in a nonequilibrium conductor originate from discreteness of the elementary charge, corresponding noise called the shot noise. Similar to Johnson-Nyquist thermometry, the shot noise measurement can be utilized for the purpose of primary, i.e. self-calibrating, noise thermometry out of thermal equilibrium. A fundamental obstacle on this route is imposed by current conservation [1], which results in a complete loss of local information in a two-terminal noise measurement. As initially demonstrated by Gramespacher and Buettiker, this restriction can be removed and local fluctuations can be picked up by means of a weakly coupled tunnel tip [2]. Apart from local thermometry, this opens ways to explore local spin accumulations [3,4] and energy distributions in a Luttinger liquid [5].

In this presentation, I will share our first results on noise measurements using an InAs semiconductor nanowire as a local noise sensor [6]. This concept is made possible thanks to elastic (energy conserving) nature of the diffusive charge transport in the nanowire, verified by conventional shot noise measurements. Our approach allows to demonstrate the shot noise of a metallic micro-strip with macroscopically large resistive terminals. In addition, the local noise thermometry turns out useful for thermoelectric [7] or spin relaxation [8] measurements of the nanowire itself.

[1] Ya. M. Blanter and M. Buttiker, Phys. Rep. 336, 1 (2000).
[2] T. Gramespacher and M. Buettiker, Phys. Rev. B 60, 2375 (1999).
[3] J. Meair, P. Stano, and P. Jacquod, Phys. Rev. B 84, 073302 (2011).
[4] T. Arakawa, J. Shiogai, M. Ciorga et al., Phys. Rev. Lett. 114, 016601 (2015).
[5] J. K. Kuhne, I. V. Protopopov, Y. Oreg, and A. D. Mirlin, Physica E 82, 293 (2016).
[6] E.S. Tikhonov, D.V. Shovkun, D. Ercolani et al., Sci. Rep. 6, 30621 (2016).
[7] E.S. Tikhonov, D.V. Shovkun, D. Ercolani et al., Semicond. Sci. Technol. 31, 104001 (2016).
[8] V.S. Khrapai and K.E. Nagaev, Pis'ma v ZhETF 105, 21 (2017).