Multimode josephson parametric converter: coupling josephson ring modulator to metamaterial

A method of operating a multimode Josephson parametric converter to generate multiple pairs of entangled photons, the method comprising:

• receiving, by a first multimode resonator in the multimode Josephson parametric converter, a first group of signals at different resonance frequencies of the resonance modes of the first multimode resonator, wherein the first multimode resonator is a first left-handed transmission line;
• receiving, by a second multimode resonator in the multimode Josephson parametric converter, a second group of signals at different resonance frequencies of the resonance modes of the second multimode resonator, wherein the second multimode resonator is a second left-handed transmission line;
• receiving pump signals, by the second multimode resonator, wherein the pump signals are a first frequency sum through a last frequency sum;
• and
• generating simultaneously pairs of entangled photons, the pairs of entangled photons including a first pair through a last pair.

A method of remote entanglement of multiple qubits by measurement, the method comprising:

• receiving, by a first multimode resonator in the multimode Josephson parametric converter, a first group of readout signals resonant with resonance modes of the first multimode resonator, wherein the first multimode resonator is a first left-handed transmission line;
• receiving, by a second multimode resonator in the multimode Josephson parametric converter, a second group of readout signals resonant with resonance modes of the second multimode resonator, wherein the second multimode resonator is a second left-handed transmission line;
• receiving pump signals, by the second multimode resonator, wherein the pump signals are a first frequency sum through a last frequency sum;
• and
• generating, by the Josephson parametric converter, a first qubit pair based on the first frequency sum through a last qubit pair based on the last frequency sum.

A method of generating a bell state using photons as quantum bits, the method comprising:

• providing a first multimode resonator and a second multimode resonator both connected to a dispersive nonlinear medium, wherein the first multimode resonator is a first left-handed transmission line and the second multimode resonator is a second left-handed transmission line, wherein resonance modes are identical in the first and second multimode resonators;
• receiving, by the second multimode resonator, a pump signal at a frequency sum, the frequency sum is a summation of a resonance frequency of the resonance modes plus a another resonance frequency of the resonance modes;
• and
• generating a first photon and a second photon in an equal superposition of spatial states, the equal superposition of the spatial states for the first and second photons are related to being in the first multimode resonator and the second multimode resonator.