Fault-tolerant cluster state quantum computation

A device for fault-tolerant quantum computation comprising:

• (a) a quantum emitter implementing a control qubit;
• (b) a first router coupled to the quantum emitter;
• (c) a second router coupled to the quantum emitter;
• (d) a first delay line coupled to the first router and the second router,
• (e) a second delay line coupled to the first router and the second router;
• and
• (f) a detector coupled to the first router;
• wherein the first delay line, the second delay line, the first router, the second router, and the quantum emitter are configured to form two loops to support propagating modes implementing data qubits that passively interact multiple times with the control qubit to generate three-dimensional cluster states;
• wherein the quantum emitter implementing the control qubit is configured to generate the propagating modes implementing data qubits;
• wherein the first router and the second router are configured such that a propagating photon or phonon travels through each of the first delay line and second delay line a predetermined number of times before being measured by the detector;
• wherein the detector is configured to measure data qubits after multiple interactions with the control qubit.