Troubleshooting

This section outlines common errors and concerns encountered when using Quantum Opus systems. For further assistance or service, please contact support@quantumopus.com. Scientists at Quantum Opus are committed to helping you optimize your measurement for your specific needs.

If electrical glitch-noise seems to be contributing to the dark count rate, please try the following suggestions to reduce this effect.

1. Remove any switching power supplies from the AC circuit that powers the Opus One system and electronics. Common culprits are small, cheaply made power supplies that run LED light strips, mobile-phone chargers, and laptops.

2. Disconnect the USB cable while monitoring the noise. If the noise drops, work on improving the grounding between the computer and Quantum Opus electronics. In particular try both configurations of powering the computer from the same circuit that run the electronics, and from a different circuit observing any change in noise.

3. Try moving other electronics off of the circuit that powers the Opus One and Quantum Opus electronics.

4. If using a stand-alone QOELEC, these suggestions may also help to reduce electrical glitch-noise:

   Ensure that there is a good connection between the ground terminal on the back of the QOELEC (screw terminal on the rear of the system) and the stainless steel helium lines on the back of the Opus One unit.

   Ensure that you are using the provided double-shielded SMA cables to connect between the "Nanowire" SMA connector and the Opus One unit. This is the most critical electrical connection in the system, so the high-quality cables are essential here.

   Tighten the SMA connectors on the QOELEC and the Opus One just tighter than hand-tight (very gently tighten with an 8-mm wrench). If this connection is slightly loose, the noise can be significantly worse.

   If all other suggestions fail: work to move grounding straps or "banana" cables around to try various grounding connections between the QOELEC and the Opus One. Try many grounding locations including the Opus One front SMA connector shields, the shelf the system sits on, etc. Ground-loop issues can be time-consuming to debug, but doing so may yield significant reductions in electrical noise.

New, rhythmic, noises from the coldhead are usually signs of aging. Technicians at Quantum Opus liken these noises to a very old car, and describe them as:

• Knocking

• Pinging

• Grumbling

• Grinding

Noises like these while the system temperature stays stable and cold are not an urgent problem, but can indicate nearing the end of life for the coldhead. Gas cleanup or cold-head service requests can be made via email support@quantumopus.com to ensure your system continues to operate reliably.

If your system has started to warm spontaneously, common causes and fixes are explained below. Be sure to perform maintenance on your compressor at the manufacturer suggested intervals. Coldhead service life is typically 25,000 run hours.

1. Arrhythmic jack-hammering sounds occur during cold-head motor failure. A short power cycle of the compressor may temporarily alleviate the issue, but the presence of this noise at any time is indicative the cold-head is at the end of its life.

2. If your system has been cold for about 6 months or more and is now warming, it is likely that air has very slowly worked its way past the seals of the vacuum space. Fully warming and re-cooling the system will remove the small amounts of air that may have leaked in.

3. If your system, upon cool-down, gets cold initially and then slowly starts to warm, this often indicates that there are contaminants in the helium that are attaching to the cold head. Reach out to Quantum Opus and we can provide you with a cold trap to capture the contaminants in the helium.

4. If your system does not get sufficiently cold after 4 or more hours on the initial cool-down, this is often indicative of a worn out cold head. Contact Quantum Opus to discuss possible service options.

Even more rarely, Quantum Opus has seen cold-heads seize completely. You will not be able to hear the piston moving in the cold head. Reach out to our support in this scenario.

Issues communicating with Quantum Opus hardware are very rare. The following steps alleviate the vast majority of issues. If your concerns persist, please contact Quantum Opus.

1. Try to use a different USB cable to connect the system to your computer. Make sure a small green LED shows on the rear of the QOELEC or on the front of the Opus One. However, even if the light is green, a different cable may fix your issue.

2. More rarely, there is an issue with the computer hardware. Try restarting the PC, and if the issue persists, using another PC to connect to the Quantum Opus System.

3. If the issue still persists, try restarting the Quantum Opus electronics via power switch, and reach out to Quantum Opus for more help.

The source of light is critical to the optimal operation of nanowire devices. Ensure that the polarization of your light is optimal, the source of the light is cleanly polarized, and the source is filtered to the correct wavelength.