Specifications

All specifications can be found in the datasheet.
* See the tab “Jitter Measurement” for measurement method.

Jitter Measurement

In order to measure the jitter, we generate an electrical pulse with steep edges. This pulse gets split into two by a power splitter and sent into two different inputs of the quTAG (i.e. start and stop-X or stop-X and stop-Y).

Then we use the quTAG software to generate a startstop-histogram. We fit a Gaussian function to this histogram and determine RMS and FWHM. The single channel jitter corresponds to σ / √2 from this two-channel measurement, assuming equal Gaussian contributions from both signals. The FWHM can be obtained by the standard deviation with the relation FWHM = 2 √2 ln 2 σ ≈ 2.35 σ.

The evaluation of the measurements shown above yields the measured jitter and calculated single channel jitter for the different modes:

Extensions

Available Extensions	standard model	basic model
+ Jitter upgrade
This feature allows lower jitter at < 6.4 ps RMS on all four input channels. For lowest jitter of < 4.2 ps RMS, two channels can be combined, leaving two stop-channels of one device for measurements. For optimal jitter results, recalibration with external signals might be necessary. The single channel jitter corresponds to σ / √2 from this two-channel measurement, assuming equal Gaussian contributions from both signals. Leading to single channel jitter < 3.0 ps RMS/√2 (2 channels) and < 4.5 ps RMS/√2 (4 channels).
+ Stop channel extension
The quTAG basic features two stop channels that can be extended by up to two more flexible stop channels. The quTAG standard has all 4 stop channels enabled by default.
+ Lifetime software
This software addon enables the user to analyze lifetime measurements on the fly. It calculates the histograms, fits exponential decreases and takes response function of the system into account.
+ Correlation software
This software extension is intended for calculating the correlation function, as needed for example in Hanbury Brown-Twiss experiments or fluorescence correlation spectroscopy. Standard functions can be fitted to assess the relevant parameters.
+ Clock Input
The quTAG can be synchronized to an external clock of 10 MHz to allow more precise long-term accuracy.
+ Synchronization between devices
This extension allows you to synchronize up to 4 quTAG devices. By this, up to 16 equal stop channels are offered and behave like one device – all sharing the same clock input and time base.
+ Marker Input
This extension allows the use of additional input channels with less resolution that can be used for your trigger signals (e.g. pixel clock, line clock). These inputs are included in your timeline and help you sorting and assigning your timestamps.
+ Filters / Virtual Channels
This extension allows you to enable user-defined filters or virtual channels (e.g. coincidence and sync filters or artificial dead time). This filtering happens inside the device so that you save bandwith on your USB connection.
+ User-defined Clock frequency
Allow to use any frequency between 1-100 MHz as clock input for long-term accuracy.
+ Start Channel as Input
The start channel can be converted to another stop channel allowing the device to have 5 completely equal input channels with 1 ps resolution.
+ Divider for stop channels
This option allows you to enable a divider on all stop channels. This allows higher (periodic) frequencies to be recorded.

Additional extensions are available upon request. Customized solutions, e.g. signal outputs, are possible. Contact us for details!

Publications

• Performance Optimization and Real-Time Security Monitoring for Single-Photon Quantum Key Distribution
  T. Kupko et al., arXiv preprint (2019)
• Hong-Ou-Mandel interference between independent III-V on silicon waveguide integrated lasers
  C. Agnesi, et al., arXiv preprint (2019)
• Sub-ns timing accuracy for satellite quantum communications
  C. Agnesi et al., arXiv preprint (2019)
• Experimental demonstration of quantum advantage for one-waycommunication complexity
  N. Kumar et al., arXiv preprint (2018)
• A photonic quantum walk with a four-dimensional Coin
  L. Lorz et al., arXiv preprint (2018)
• Towards quantum communication from global navigation satellite system
  L. Calderaro et al., IOP Publishing (2018)

General Applications

Laser trigger as Start, Single Quantum SNSPD as Stop

We measured a time difference histogram between the trigger pulse from the laser as start and the SQ detector signal as stop.
This is basically the setup for a Fluorescence Lifetime Imaging (FLIM) measurement..

Results:
Whole system response function (blue, measured with quTAG): Timing jitter 17.8 ps RMS, 35.9 ps FWHM
For comparison: Detector response function (red, measured with fast oscilloscope): Timing jitter 14.5 ps RMS, 26.1 ps FWHM.

One SQ Detector as Start, another one as Stop

Here, we measured the time difference histogram between one of the two SQ SNSPDs as Start and the other one as Stop pulse.

Results:
Timing jitter of 2 SQ SNSPDs measured with the quTAG (blue): 21.6 ps RMS, 45.6 ps FWHM.

Datasheets

Software

quTAG software V1.5.0*	09/2019	25.0 MB	exe
quTAG software V1.5.0*	09/2019	20.8 MB	zip
64bit library win V1.5.0*	09/2019	0.4 MB	zip
64bit library linux V1.5.0*	09/2019	7.6 MB	tgz
FTDI driver V1.2		10.4 MB	exe
Python examples	01/2020	1.9 MB	zip

* Note! This software is compatible only with serial number T 01 0012 and newer! Please contact us if you own an older device!