Single-electron shuttle based on a silicon quantum dot

Abstract

We report on single-electron shuttling experiments with a silicon metal-oxide-semiconductor quantum dot at 300 mK. Our system consists of an accumulated electron layer at the Si/SiO2 interface below an aluminum top gate with two additional barrier gates used to deplete the electron gas locally and to define a quantum dot. Directional single-electron shuttling from the source to the drain lead is achieved by applying a dc source-drain bias while driving the barrier gates with an ac voltage of frequency fp. Current plateaus at integer levels of efp are observed up to fp = 240 MHz operation frequencies. The observed results are explained by a sequential tunneling model which suggests that the electron gas may be heated substantially by the ac driving voltage.Keywords: quantum dot, silicon, single-electron, charge pumping While the Josephson voltage and the quantum-Hall resistance standards [1,2] are routinely used in metrology institutes worldwide, the current standard is missing from the so-called quantum metrological triangle which would provide a consistency check for these three quantities. The consistency would remove any remaining doubts about the quantum standards and justify a redefinition of the International System of Units [3].A metallic electron pump with a relative uncertainty of a few parts in 10 8 in its current has been achieved by utilizing seven tunnel junctions in series, forming six gated islands [4]. However, the operation frequency was limited to the megahertz range because of adiabaticity requirements for the high number of islands. These low current signals, of the order of 1 pA, are sensitive to thermal fluctuations and hence are not satisfactory for the planned quantum metrological triangle experiments [3]. Other single-electron pumping experiments have been carried out in different systems such as hybrid normal-metal-superconductor turnstiles [5], GaAs/AlGaAs nanowire quantum dots [6], InAs nanowire double quantum dots [7], metal-oxidesemiconductor field-effect transistors (MOSFETs) in Si nanowires [8], and GaAs quantum dots [9].In this paper, we employ a silicon quantum dot [10] shown in Fig. 1(a,b) as a test-bed for the current source. The device was fabricated on a high-resistivity (ρ > 10 kΩ cm at 300 K) silicon substrate. An industry-compatible MOSFET fabrication process is adapted to realize our quantum dot system [11]. The source and drain were thermally diffused with phosphorus and a high-quality gate oxide was grown thermally yielding a low Si/SiO 2 interface trap density of * Electronic

An Accurate Single-Electron Pump Based on a Highly Tunable Silicon Quantum Dot

“…This device ideally generates a quantized output current, I P = nef , where n is an integer and f is the frequency of an external periodic drive. Several enabling technologies have already been developed including metal/oxide tunnel barrier devices 6,7 , normal-metal/superconductor turnstiles 8,9 , graphene double quantum dots 10 , donor-based pumps [11][12][13] , silicon-based quantum dot pumps [14][15][16][17][18] and GaAs-based quantum dot pumps [19][20][21][22][23][24][25][26][27] . To date, the latter scheme provides the lowest uncertainty of 1.2 parts per million (ppm) yielding current in excess of 150 pA 27 .…”

Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling

“…16 As a result, Si spin QC has emerged as an active subfield of modern condensed matter physics. Outstanding experimental progress in Si spin QC has been reported in the last few years in Si quantum dots (QDs), [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and in donor-based architectures. [36][37][38][39][40][41][42][43][44][45][46][47][48] Theoretical research on Si QDs has also evolved at a brisk pace.…”

Spin-selective electron transfer in a quantum dot array

“…Various types of qubit operations have been demonstrated [10][11][12], including two-qubit logic gates using the exchange interaction between single spins in isotopically enriched silicon [13]. On the other hand, single-electron pumps [14][15][16][17][18][19][20] and the shuttling of single electron [21,22] in quantum dots have also been demonstrated at metrological accuracy. In fact, single-spin shuttling in a GaAs system quantum dot array has recently been demonstrated using this shuttling operation, and has been shown to preserve the spin coherence up to macroscopic distances [22].…”

“…In this paper, we propose a scheme for spin-selective coherent electron transfer in a quantum dot array achievable using the proven experimental techniques in single-spin shuttling [21,22] in a silicon qubit architecture [11][12][13]. The gradient of oscillating magnetic fields and controlled gate voltages are utilized to separate the electron wave function into different quantum dots in a spin-selective manner.…”