Superconducting Quantum Processors

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We develop superconducting quantum circuits for quantum information applications using Josephson junction technology. Our focus is on designing and fabricating circuits with the goal of implementing quantum algorithms and quantum simulations.


We build quantum processors out of superconducting quantum circuits. Superconducting qubits are built using Josephson junctions, which are nonlinear, nondissipative elements that generate an anharmonic spectrum of the circuit. The Josephson tunnel junction is a very thin superconductor-insulator-superconductor barrier that permits tunneling of the superconducting wave function across it. In engineering language, it behaves as a nonlinear inductor.

Superconducting qubits are obtained out of two of the states of the Josephson circuit nonlinear spectrum. There exist different types of superconducting qubits depending on whether the Josephson energy stored in the junction dominates over the capacitive energy. The most widely used qubits are the persistent current flux qubit and the Cooper pair box transmon qubit.

Superconducting qubits coupled to resonators are the on-chip analogue of single atoms coupled to single photons in a cavity, in the microwave regime of energies. In atom-photon cavity QED, the highest couplings achieved are 10-6 times smaller than the cavity frequency, while superconducting qubits can easily attain 10-2, entering regimes where unexplored physics take place. A nice and complete review of quantum optics with superconducting qubits can be found here.


Our main goal is to build a small-sized quantum processor made of tens of superconducting quantum bits, or qubits. With such a processor we will implement the quantum algorithms specifically developed. For more details visit our group website

    • POL FORN DIAZ's picture
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    • Tel: +34 934054303
    • pol [dot] forndiaz [at] bsc [dot] es