Figure 1
APS/Alan Stonebraker

Figure 1: Conceptual illustration of linear optical quantum computing in a single spatial mode [1]. A long string of single-photon time-bin qubits propagates down a single waveguide (like a fiber), and the polarization degree of freedom is used to switch various time bins into a “processing mode” for qubit operations, logic gates, and detection. The inset to the figure illustrates a new method for ultrafast detection of time-bin qubits in which chirped laser pulses and sum frequency generation are used to coherently map the time bins into frequency bins [2].