Nanoscale Physics
Differential conductivity of surface electrons over superfluid helium in potential wells of charged profiled substrate   
V. A. Nikolaenko1, A. S. Smorodin2, S. S. Sokolov1
1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Prospekt Nauky, 47, Kharkov 61103, Ukraine  
2 Okinawa Institute of Science and Technology, Okinawa 904-0495, Japan
E-mail: nikolaenko@ilt.kharkov.ua 
The contemporary nano-technologies have lead to creating Q1D conducting systems: charges move free in one direction and others displacement are quantized. The study of Q1D system in semiconductors motivated creating this system based on the surface electrons over helium - SE. The advantages of SE’s are high homogeneity, wide variation in separate experiment both the electron density and the width of conducting lines. The Q1D system over helium at pressing field, E┴ in grooves of profiled substrate was proposed and realized in [1] and detailed in [2]. 
         
In this work the electrons from a source emitted to substrate forming stripes and then into grooves with helium for forming SE lines. The depth of potential well for SE estimated φ ~ e E┴ δ (δ is deflection of liquid surface in groove at radius R) and spectrum is . The stripes shift SE spectrum as ω2 ~ π2e2nx/ma2 (nx  is linear charge density and a is distance between charges). The temperature dependence of conductivity, σ at potentials of charge and SE 15V has steplike behavior at T<1.4K (left figure). Observed feature isn't described by scattering SE on helium atoms in gas or on ripplons. Differential of σ corresponding state density is shown on right picture. These dependences demonstrate in some approach behave of Q1D system. The energy steps  ħ·ω (ħ is Plank’s constant) is according to dif σ minimum. Parameters of the steps in various experiments were various.    

1.	Yu. Z. Kovdrya, Monarkha Yu.P. 1D electron system over liquid helium // Fiz. Nizk.Temp.–1986.-12.- P.1011-15; Yu. Z. Kovdrya, V.A. Nikolaenko. Q1D electron system over liquid helium //Fiz. Nizk.Temp. –1992.-18.- P.1278-80.
2.	S.S. Sokolov, Guo-Qiang Hai and Nelson Studart. Mobility of electrons in Q1D channel on the liquid helium surface //PRB. -1995. -51. -P.5977-88.