EPS-1000-W

The entangled photon source (EPS) is an easy-to-use source of fiber-coupled polarization entangled photons in the 1550 nm band. The EPS-1000-W generates polarization entangled signal-idler pairs as well as a sequence of polarized alignment signals to aid in aligning subsequent measurement equipment (software selects if entangled photons or alignment photons are generated). The alignment signals allow measurement bases of polarization analyzers to be aligned despite unknown polarization transfer functions of the output fibers. The system is pulsed at a frequency-lockable and tunable repetition rate, allowing multiple EPS’s to be synchronized for quantum interference experiments. Signal/idler photons are each generated over a 16 nm bandwidth, and ITU-grid filters are included to capture N photon pairs on 2⋅N fibers (N=3 is standard, but higher values available). The filtering system can be bypassed to allow customers to use their own filters. Many customizations are possible, including time-bin entangled versions and tunable pump pulse-width / wavelength, so please enquire about your particular needs.

Alignment Signal Operation - more information

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Basic Features

Fiber-coupled Signal and Idler photons on the DWDM ITU grid Can generate alignment signals to compensate for fiber polarization transformations Computer-controlled two-photon generation rate Electrical optical clock output signals available

Product Specifications

Attribute	Value	Units	Comments
Pulse Rate	50 - 1,250	MHz	Extended rates available; electrical input and output signal for frequency-locking
Filter-isolated Photon Pairs	2 - 4	#	2⋅N: Number of ITU grid photon pairs isolated by filtering system; LC connectors standard
Filter Bandwidth	0.3	nm	ITU grid
Signal (or Idler) Spectral Bandwidth	16	nm	Central Wavelengths symmetric with respect to pump wavelength
Pump Wavelength	1550.4	nm	Typical value; others available as an option
Pump Pulse-Width	100	ps	Typical value; other values available by request
Pair Emission Probability (p)	5·10-3to 10-4		Probability each photon pair is emitted out of the filters (100 MHz rate); Entanglement quality depends on p**;
CAR	10 to >100		Coincidence to accidental count ratio (CAR); depends on p
Form Factor	3	U	3U 19" rack-mountable box; 19x5.4x24 inches

* Specifications are estimates subject to change without notice **p is defined as the probability a pulse will emit a photon pair out of the filtering system (probability of a coincidence count using detectors of 100% quantum efficiency). Measured coincidence count rate through aligned polarization analyzers is CCmeas ≈ R⋅ 0.5⋅ p⋅ η2, where R is the pulse repetition rate and η is the net detection efficiency of a photon of optimal polarization from the EPS output (including single photon detection efficiency). Assuming R = 100 MHz, p=10-3, and η = 40%, the coincidence count rate is expected to be 8,000 per second for each photon pair.

Typical Applications

Quantum Communications over Fiber Quantum Cryptography Quantum Imaging (Ghost Imaging) Quantum Metrology Quantum Networking

Product Photo & Diagrams

Example Two-Photon Interference measurement: 50 MHz gated sing-photon avalanche diode (SPAD) detector, 1 second/point (peak is ~2 coincidence counts per million gates).

Example Quantum State Tomography: 50 MHz gated SPAD, measured coincidence count maximum ~6 per million gates.

EPS-1000-W Face Plate