A capacitively coupled SFQ Josephson memory cell

Abstract

This paper presents the design and experimental results of a new type of Josephson memory cell. It has a simpler construction than the conventional Henkels-type memory cell, using a one-junction SQUID capacitively coupled to a single junction. Binary data are stored as a single flux quantum in the one-junction SQUID, and are destructively read out by sensing a pulse caused by a vortex-mode transition. Computer simulations suggested that the READ operation could be performed with a bias margin for the sense junction of *28 percent, and also that the rise time of the sense current in a 16-bit memory cell would be as fast as 30 ps despite having to sense a vortex-mode transition. We provide results of a memory cell fabricated with Nb/AIO,/Nb junctions. '

Experimental demonstration of a Josephson cryogenic memory cell based on coupled Josephson junction arrays

“…The largest memory circuit to date was approximately 4 kb and was based on vortex transition memory cells [5][6][7][8][9]. Other than the vortex transition cell, numerous other types of flux-based memory cells have also been developed previously [10][11][12][13][14]. New memory devices have been developed including based on magnetic junctions [15][16][17][18][19][20], f-Josephson junctions [21], photon modulated cells [22], superconducting frustration bits [23], hybrid magnetic cells [24], adiabatic quantum flux parametron cells [25], cells with 0-and p-junctions [26], integrated ferromagnetic and superconducting junction cells [27,28], spin-torque transfer cells [29].…”