Ultra-low noise quantum frequency conversion for trapped ion quantum network

A method of generating entangled photons with wavelengths in the telecommunication range, the method comprising:

• generating first entangled photons from a trapped ion, a single-photon source, or a quantum emitter;
• interacting one of the first entangled photons with second photons of a first pump laser in a first non-linear medium of a first quantum frequency conversion device, thereby generating a third photon having a longer wavelength than the first entangled photons;
• and
• interacting the third photon with fourth photons of a second pump laser in a second non-linear medium of a second quantum frequency conversion device, thereby generating a fifth photon having a longer wavelength than the third photon,
• wherein a wavelength of the fifth photon is in the telecommunication range (1260 nm to 1675 nm), and
• wherein a signal-to-noise ratio (SNR) of the fifth photon upon exiting the second quantum frequency conversion device is at least 1.

A quantum network comprising:

• two or more quantum computers, wherein each quantum computer is separated from another quantum computer in the quantum network by a distance of at least one meter;
• two or more quantum modems, wherein each quantum modem is coupled to a quantum computer and configured to convert emitted entangled photons produced by the quantum computer into telecommunication photons (1260 nm to 1675 nm) through one or more quantum frequency conversion devices;
• and
• a quantum router configured to couple one quantum computer and quantum modem to another quantum computer and quantum modem through optical telecommunication fibers,
• wherein the telecommunication photons have a signal-to-noise ratio (SNR) of at least 1.