Experimental studies of clocked quantum-dot cellular automata devices

• Published in: 58th DRC. Device Research Conference. Conference Digest (Cat. No.00TH8526) pp. 157 - 158
• Main Authors: Orlov, A.O., Toth, G., Amlani, I., Kummamuru, R., Ramasubramaniam, R., Lent, C.S., Bernstein, G.H., Snider, G.L.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2000
• Subjects: Clocks; Control systems; Current measurement; Electrons; Logic devices; Power dissipation; Quantum cellular automata; Quantum computing; Quantum dots; Tunable circuits and devices
• ISBN: 9780780364721; 0780364724
• DOI: 10.1109/DRC.2000.877130

Devices based on the quantum-dot cellular automata (QCA) computational approach (Lent et al, 1993) use interacting quantum dots to encode and process binary information. In this transistorless approach to computation, logic levels are represented by the configurations of single electrons in coupled quantum-dot systems. In the last few years, significant progress has been made towards the realization of basic QCA elements. However, in these devices, power gain needed for the operation of large QCA arrays was not possible since the only source of energy was the signal input. Recent theoretical work (Lent and Tougaw, 1997) proposed clocked control of the QCA circuitry. Clocked controlled QCA systems have many advantages such as power gain, reduced power dissipation, and pipelined architectures. The original theoretical work applied only to semiconductor implementation of clocked QCA arrays, but recently a scheme for clocked control of metallic QCA cells was proposed (Toth and Lent, 1999; Korotkov and Likharev, 1998). Here an extra dot placed between the two dots of the QCA half-cell acts as a tunable barrier controlled by the clock signal. We present the experimental demonstration of a clocked QCA cell. The device consists of two capacitively coupled half-cells, where each half-cell consists of three micron-size Al islands separated by tunnel junctions, and four electrometers to measure the charge state of the half-cells. The half-cells are leadless, with no DC connection to the environment.