Superconducting quantum bits

  title={Superconducting quantum bits},
  author={John Clarke and Frank K. Wilhelm},
Superconducting circuits are macroscopic in size but have generic quantum properties such as quantized energy levels, superposition of states, and entanglement, all of which are more commonly associated with atoms. Superconducting quantum bits (qubits) form the key component of these circuits. Their quantum state is manipulated by using electromagnetic pulses to control the magnetic flux, the electric charge or the phase difference across a Josephson junction (a device with nonlinear inductance… 

Topological quantum memory interfacing atomic and superconducting qubits

We propose a scheme to manipulate a topological spin qubit which is realized with cold atoms in a one-dimensional optical lattice. In particular, by introducing a quantum opto-electro-mechanical

Superconducting Circuits for Quantum Information: An Outlook

For the first time, physicists will have to master quantum error correction to design and operate complex active systems that are dissipative in nature, yet remain coherent indefinitely.

Circuit QED and engineering charge-based superconducting qubits

The last two decades have seen tremendous advances in our ability to generate and manipulate quantum coherence in mesoscopic superconducting circuits. These advances have opened up the study of

Quantum Simulations with Circuit Quantum Electrodynamics

Superconducting circuits have become a leading quantum platform for the implementation of quantum information tasks. Here, we revise the basic concepts of circuit network theory and circuit quantum

Materials in superconducting quantum bits

Superconducting qubits are electronic circuits comprising lithographically defined Josephson tunnel junctions, inductors, capacitors, and interconnects. When cooled to dilution refrigerator

Electronic structure of superposition states in flux qubits

Flux qubits, small superconducting loops interrupted by Josephson junctions, are successful realizations of quantum coherence for macroscopic variables. Superconductivity in these loops is carried by

Protecting superconducting qubits with a universal quantum degeneracy point

Low-frequency noise can induce serious decoherence in superconducting qubits. Due to its diverse physical origins, such noise can couple with the qubits either as transverse or as longitudinal noise.

Realizing quantum gates and algorithms with three superconducting qubits

Superconducting quantum circuits have become a promising architecture for the potential realization of a scalable quantum computer. These circuits consist of capacitors, inductors and Josephson

A quantum engineer's guide to superconducting qubits

The aim of this review is to provide quantum engineers with an introductory guide to the central concepts and challenges in the rapidly accelerating field of superconducting quantum circuits. Over

Superconducting Quantum Computing Without Entanglement

In recent years, quantum computing has promised a revolution in computing performance, based on massive parallelism enabled by many entangled qubits. Josephson junction integrated circuits have



Quantum Coherent Tunable Coupling of Superconducting Qubits

This work reports on the time-domain tunable coupling of optimally biased superconducting flux qubits by modulating the nonlinear inductance of an additional coupling element and parametrically induced a two-qubit transition that was otherwise forbidden.

Vacuum Rabi oscillations in a macroscopic superconducting qubit oscillator system.

The coherent exchange of a single energy quantum between a flux qubit and a superconducting LC circuit acting as a quantum harmonic oscillator is observed and the idea of using oscillators as couplers of solid-state qubits is supported.

Quantum oscillations in two coupled charge qubits

This work demonstrates the feasibility of coupling multiple solid-state qubits, and indicates the existence of entangled two-qubit states, and demonstrates a Josephson circuit consisting of two coupled charge qubits.

Manipulating the Quantum State of an Electrical Circuit

A superconducting tunnel junction circuit that behaves as a two-level atom that can be programmed with a series of microwave pulses and a projective measurement of the state can be performed by a pulsed readout subcircuit is designed and operated.

Rabi oscillations in a large Josephson-junction qubit.

A circuit based on a large-area current-biased Josephson junction whose two lowest energy quantum levels are used to implement a solid-state qubit is designed and operated and is the basis of a scalable quantum computer.

Josephson-junction qubits with controlled couplings

Quantum computers, if available, could perform certain tasks much more efficiently than classical computers by exploiting different physical principles. A quantum computer would be comprised of

Demonstration of conditional gate operation using superconducting charge qubits

This work demonstrates conditional gate operation using a pair of coupled superconducting charge qubits using a pulse technique and shows that their amplitude can be transformed by controlled-NOT (C-NOT) gate operation, although the phase evolution during the gate operation remains to be clarified.

Demonstration of controlled-NOT quantum gates on a pair of superconducting quantum bits

Selective execution of the complete set of four different controlled-NOT (CNOT) quantum logic gates are demonstrated, by applying microwave pulses of appropriate frequency to a single pair of coupled flux qubits, to form an efficient set of versatile building blocks.

Measurement of the Entanglement of Two Superconducting Qubits via State Tomography

A high degree of unitary control of the system is demonstrated, indicating that larger implementations are within reach of entanglement between two solid-state qubits.

Observation of quantum oscillations between a Josephson phase qubit and a microscopic resonator using fast readout.

The results reveal a new aspect of the quantum behavior of Josephson junctions, and they demonstrate the means to measure two-qubit interactions in the time domain.