Characterization of energy potential in tunable rf-SQUIDs with the classical regime toward precise design of superconducting flux qubit

Abstract

The detailed characteristics of classical states in a radio-frequency superconducting quantum interference device (rf-SQUID) with well-designed energy-potential shape are investigated at 4.2 K. Using Nb/AlO x standard process which enables precise circuit-parameter implementation, the rf-SQUID is designed in its energy potential. Directions of persistent current can be distinguished in the rf-SQUID we have fabricated. Analyses in circuit simulations indicate the device design based on enough high critical current provides available parameters to construct the device for 10 mK measurement by circuit-parameter scaling. This knowledge may contribute to the precise design of the rf-SQUID for superconducting qubit through device process with lower critical current density.

Experimental Demonstrations of Native Implementation of Boolean Logic Hamiltonian in a Superconducting Quantum Annealer

“…The main reason is the existence of a local minimum in an energy potential of each qubit. To avoid generation of local minima in energy potentials, the value of a dimensionless factor L = 2LIc/0, where L is the inductance, should be less than 8 [19]. Since the L of the multiplier was 10.8, an unintentional trap to the local minimum occurred during the annealing process, resulting in incorrect multiplier responses.…”

Scalable Interconnection Using a Superconducting Flux Qubit

“…An alternative method that is particularly suitable for solving combinatorial optimization problems is using quantum circuits for quantum annealing (QA). The advantages of quantum computation using QA over conventional methods are still under investigation, but practical demonstrations will be available in the near future [3][4][5][6][7][8][9][10][11][12][13][14] . A superconducting ux qubit is used in QA [3][4][5] .…”

Superconducting quantum circuit of NOR in quantum annealing

“…An alternative method, that is particularly suitable for solving combinatorial optimization problems, is the use of quantum circuits for quantum annealing (QA). Though a testimony of computational advantage over conventional methods in QA has been still under consideration, QA provides the most practical demonstration of quantum computation in the near term 4 – 14 . When expressing problems to be solved, QA uses a Hamiltonian with a time-dependent term for initializing the ground state.…”