In the Linear Optics approach to Quantum Computation (LOQC), qubits are encoded in quantum states of entangled photons. At the same time, algorithmic transformations are performed with linear optical elements such as beam splitters, phase retarders, and mirrors. Two-qubit gates are implemented by combining linear optical elements in a clever way with single-photon detectors and post-selection. The detectors project and measure the quantum states of single photons and thereby introduce effective non-linearities. In practice, computation results in LOQC experiments are extracted by detecting and correlating individual photons at the system output.
The most common single-photon detectors are Single-Photon Avalanche Diodes (SPADs) and Superconducting Nanowire Single-Photon Detectors (SNSPDs). SPADs have good quantum efficiency (up to 70 % around 700 nm), low dark count rates, are compact and easy to use. SNSPDs have further advanced the detection performance with quantum efficiencies in excess of 90 % and timing resolution down to 15 ps. The electric outputs of single-photon detectors result in massive streams of single-photon trigger events. Leading researchers around the world employ Swabian Instruments' Time Taggers to detect multi-coincidence events in such data streams on-the-fly and continuously extract quantum information.
Swabian Instruments' Time Tagger Ultra Series enables you to synchronize up to 8 units, each with 18 channels, to process signals from up to 144 single-photon detectors. The hardware-based conditional filter allows reducing data-rates by capturing only the detection events relevant to your measurement. Features provided by the Time Taggers' software engine include flexible delay tuning on each channel independently so that the sync signal and all detected events can be properly time adjusted for coincidence measurement.
Swabian Instruments' programming libraries enable you to acquire data and perform analysis in your favorite programming language. Complex, multi-fold coincidence measurements can be performed on-the-fly and with ease using built-in virtual channels. When required, the software engine allows storing every detected event for data archival purposes or offline processing.
Whether you are using SPADs or SNSPD, the Time Tagger Series' flexible input stages allow you to interface all your detectors seamlessly while taking advantage of the highest rise time of your signals. The high time resolution ensures that you are ready for new low jitter detectors available in the future.
Build upon a powerful software library that can be easily extended. You can rapidly implement your research ideas. Researchers at the University of Oxford, for example, have implemented their own on-the-fly processing plug-in that runs with a single Time Tagger Ultra and is capable to measure more than 500 higher-order coincidence rates on-the-fly, that is generated by a linear optics quantum chip.