Josephson junction count


The Josephson junction count is the number of Josephson junctions on a superconducting integrated circuit chip. Josephson junctions are active circuit elements in superconducting circuits. The Josephson junction count is a measure of circuit or device complexity, similar to the transistor count used for semiconductor integrated circuits.
Examples of circuits using Josephson junctions include digital circuits based on SFQ logic, superconducting quantum computing circuits, superconducting analog circuits, etc.

Integrated circuits

The superconducting integrated circuits listed here must have been fabricated and tested, but are not required to be commercially available. Chip area includes the full extent of the chip.
ReferenceDescriptionJunction
count		DateMakerProcessCircuit
Chip
RSFQ NOT gate131987Moscow State U.10 µm, 5 MA/m², 2 Nb1.1
CORE1α6RSFQ microprocessor, 8 bit6,3192004NEC2 µm, 25 MA/m²10.9
SCRAM2RSFQ microprocessor, 8 bit8,1972006SRL2 µm, 25 MA/m²15.325
CORE1γRSFQ microprocessor, 8 bit22,3022007ISTEC2 µm, 25 MA/m²40.4564
RainierRSFQ, 128 qubit QA processor23,3602010D-Wave, SVTC250 nm, 2.5 MA/m², 6 Nb832
VesuviusSFQ, 512 qubit QA processor96,0002012D-Wave, SVTC250 nm, 2.5 MA/m², 6 Nb8162
RSFQ, 16-bit adder12,7852012SBU, AIST1 µm, 100 MA/m², 10 Nb8.529.75
8,192 bit shift register32,8002014SBU, MIT-LL500 nm, 100 MA/m², 8 Nb925
Washington SFQ, 2048 qubit QA processor128,4722015D-Wave, Cypress250 nm, 2.5 MA/m², 6 Nb30.3136
RQL, 2 shift registers72,8002015NGC, MIT-LL500 nm, 100 MA/m², 8 Nb925
16000 bit shift register65,0002016SBU, MIT-LL500 nm, 100 MA/m², 8 Nb1225
36000 bit shift register144,0002016SBU, MIT-LL350 nm, 100 MA/m², 8 Nb1525
202280 bit shift register809,1502016SBU, MIT-LL350 nm, 100 MA/m², 8 Nb64100
Pegasus P16SFQ, 5640 qubit QA processor1,030,0002020D-Wave, SkyWater Technology250 nm, 2.5 MA/m², 6 Nb70.6

Maker column may include organizations that designed and fabricated the chip.
Process column information: minimum linewidth, Josephson junction critical current density, superconducting layer number and materials.
Conversions for units of critical current density: 1 MA/m2 = 1 µA/µm2 = 100 A/cm2.

Memory

Memory is an electronic data storage device, often used as computer memory, on a single integrated circuit chip. The superconducting integrated circuits listed here must have been fabricated and tested, but are not required to be commercially available. Chip area includes the full extent of the chip.
ReferenceDescriptionJunction
count		DateMakerProcessCircuit
Chip
1024 bit ROM, NbN/MgO/NbN junctions5,9431990Electrotechnical Lab, Japan3 µm, 5.6 MA/m², 2 Nb + 1 Pb-In17.25
4096 bit RAM23,4882005ISTEC1 µm, 100 MA/m², 10 Nb5.5