Bit error rate experiments in ring-shaped RSFQ circuits

The reduction of the critical current density in rapid single-flux quantum (RSFQ) circuits enables new application fields, like quantum computing and photonic detector readout. The low current density fabrication process creates new design challenges, such as lower stability against thermal fluctuations, violation of the lumped elements condition for microstrip inductances and increased sensitivity to the technological spread. To overcome these issues, we suggest a passive phase shifter as a promising alternative technique for superconductive phase dropping in the RSFQ electronics. Here, we study experimentally their applicability in high-speed RSFQ digital circuits. Conclusions are drawn about the impact of the passive phase shifters on the complexity, the speed and the bit error rate of the investigated RSFQ circuits. We demonstrate the successful operation of different circuits with implemented passive phase shifters at low and high speeds.

Section: Bit Error Rate Testing Of a Toggle Flip-flop With Passive Ph...supporting

confidence: 53%

Section: Bit Error Rate Testing Of a Toggle Flip-flop With Passive Ph...mentioning

confidence: 99%

Implementation of superconductive passive phase shifters in high-speed integrated RSFQ digital circuits

Dimov

Balashov

Khabipov

et al. 2008

“…Fabrication of the integrated circuits began with the preparation of the conventional SFQ part of the circuit, applying the technological process based on the PTB production line developed for the fabrication of externally shunted Josephson junctions (JJs) in 4 μm Nb/Al-Al x O y /Nb trilayer technology [18]. Thermally oxidized three-inch silicon wafers were used as substrates.…”

Section: Circuits Fabricationmentioning

confidence: 99%

A single flux quantum circuit with a ferromagnet-based Josephson π-junction

Khabipov¹,

Balashov²,

Maibaum³

et al. 2010

We report on the functionality of a Nb-based superconducting single flux quantum (SFQ) toggle flip-flop (TFF) circuit, comprising a complementary superconductor-ferromagnetsuperconductor (SFS) Josephson π-junction. The SFS junction was used as a phase shifting element inserted in the storage loop of the TFF. The fabricated circuits demonstrated correct functionality with the operation parameter ranges of ±20%. The application of SFS π-junctions makes the SFQ circuits very compact, may substantially improve their stability, and may also be suitable for integration with Josephson quantum circuits (qubits).

“…, J 10 , together with the connecting inductances). In principle, the SFQ pulses can also be received from a circular shift register which enables a wide range for the adjustment of pulse duration and frequency, due to appropriate binary code circulation [3,17].…”

Section: Circuit Design and Fabrication Technologymentioning

confidence: 99%

Rapid single-flux quantum control of the energy potential in a double SQUID qubit circuit

Castellano

Chiarello

Leoni

et al. 2007

We report on the development and test of an integrated system composed of a flux qubit and a rapid single-flux quantum (RSFQ) circuit that allows qubit manipulation. The goal is to demonstrate the feasibility of control electronics integrated on the same chip as the qubit, in view of the application in quantum computation with superconducting devices. RSFQ logic relies on the storage and transmission of magnetic flux quanta and can be profitably used with superconducting qubits because of the speed, scalability, compatibility with the qubit fabrication process and low temperature environment. While standard RSFQ circuitry is well assessed, the application to quantum computing requires a complete rescaling of parameter values, in order to preserve the qubit coherence and reduce the power dissipation. In the system presented in this paper, the qubit role is played by a superconducting loop interrupted by a small dc SQUID, usually called a double SQUID, which behaves as a tunable rf-SQUID. Its energy potential has the shape of a double well, with the barrier between the wells controlled by magnetic flux applied to the inner dc SQUID. Here for the first time we report measurements at a base temperature of 370 mK in which flux control pulses with desired characteristics were supplied by a RSFQ circuit fabricated using non-standard parameters in the same chip as the qubit.