QCA Lecture 6

A perfect conductor is necessarily a superconductor

• Yes

• No

Which superconductor is mostly used for qubits?

• Nb

• Al

• Pb

• Ti

In which energy range is in the gap of a superconductor (like Al or Pb) @T=0?

• 1 \mu eV- 10  \mu eV

• 100 \mu ev - 1 meV

• 10 meV-100 meV

• 1 eV-10 eV

Which is not true for a Josephson tunnel junction?

• The critical current is temperature dependent.

Why do they use SQUIDs for SC qubits?

• To sense magnetic fields.

• To have tunable qubit freqency.

• To be resistive against temperature fluctuations.

• To be resistive against magnetic field fluctuation.

Josephson junctions are non-linear inductors.

• True

• False

For a charge qubits the phase is well defined.

• True

• False

For a charge qubit E_c>>E_J.

• True

• False

By doubling the area of a tunnel junction, the Josephson energy

• does not change.

• increases by a factor of 2.

• increases by a factor of 4.

• decreases by a factor of 4.