Case Study CS-TC03 Rev. A

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The value at 0 decay can show the number of modes in the

cavity, N:

(3)

giving a single mode value (N=1) of G(2)(0) = 2.

Figure 5

shows the delays calculated from the TTM recordings.

From this plot, the peak value at 0 decay is 1.942 ± 0.001,

corresponding to single-frequency-mode operation.

Another parameter that is used to characterize photon

sources is the heralded or conditional second-order

correlation function, g(2)(τ). Detection of the signal photon

is heralded (or known to be detected) by the detection

of a idler photon. An ideal single-photon source will have

g(2)(0) = 0. The data from this study recorded a value of

g(2) = 0.04 ± 0.01 at 1 mW of pump power showing an

almost perfect single-photon source without higher order

emissions.1

At 10 mW of pump power, researchers recorded 2.5 kHz

2-fold coincidence counts. This translates to a photon-pair

generation rate of 47.5 kHz leading to a spectral brightness

of 436 s-1 mW-1 MHz-1. This rate surpasses all previously

known research of single-mode photon pair generation

while maintaining the high level of purity. This method

reduces losses known to previous systems and provides

solutions for many quantum applications.

G(2) (0) = 1 + 1N

WAVELENGTH'S ROLE

The Optical Parametric Oscillator (OPO) is highly

dependent on the temperature of the crystal. Changing

temperature alters the index of refraction which changes

the wavelength of the light. The crystal can also change

length due to temperature, causing a shift in efficiency and

cluster tuning capabilities. Temperature regulation of both

crystals in the OPO cavity is essential.

Wavelength Electronics' PTC5K-CH (

Figure 6) provides a

current limit of 5 A with multiple features and benefits. In this

application it controlled the temperature of the crystals in

the OPO cavity with precision better than 2 mK, generating

the necessary crystal stability.

The PTC5K-CH temperature controller operates from

a single power supply between 5 V and 30 V. The linear

bipolar controller can drive a Peltier thermoelectric cooler or

a resistive heater, and integrates easily into the system. It

can stabilize temperature to 0.0012ºC.

The compact chassis mount design simplifies heatsinking

and requires minimal space. The PTC5K-CH can be

found in systems in diverse applications such as particle

and droplet measurement, biomolecular interaction

analysis, manufacturing machine vision systems, and now

single-mode narrow-bandwidth photon sources for hybrid

quantum applications.

Figure 5. Experimental Autocorrelation with Fit Curve1

Figure 6. PTC5K-CH Temperature Controller