Systems and methods for measurement-device-independent quantum key distribution

A hub for a measurement-device-independent quantum key distribution network, comprising:

• a wavelength-calibration laser;
• an optical splitter configured to split an output of the wavelength-calibration laser into first and second wavelength-calibration signals;
• a first optical output configured to transmit the first wavelength-calibration signal to a first node of the quantum key distribution network;
• a second optical output configured to transmit the second wavelength-calibration signal to a second node of the quantum key distribution network;
• and
• a Bell-state measurer configured to perform a Bell-state measurement with first and second photonic qubits received from the first and second nodes, respectively.

A node for a measurement-device-independent quantum key distribution network, comprising:

• an optical circulator having a first port, a second port, and a third port, the optical circulator being configured to (i) emit, from the second port, light coupled into the first port and (ii) emit, from the third port, light coupled into the first port;
• a qubit encoder configured to encode a logical qubit in each of a sequence of optical pulses emitted from the second port of the optical circulator to create a sequence of photonic qubits;
• and
• a calibrator configured to couple a wavelength-calibration signal from a hub of the quantum key distribution network into the third port of the optical circulator such that the wavelength-calibration signal is emitted from the first port of the optical circulator.