A few weeks ago, I was a mentor for the NYU Abu Dhabi Quantum Hackathon for Social Good in the Arab World. My team, called the Quantum Sensing Pirates, attempted to build QvsPy: A simulator for programmable quantum sensors. We ran out of time to make our simulator programmable so we simulated a quantum sensor for COVID detection instead. Why work on a sensing project at a quantum computing hackathon? Well, a quantum sensor is similar to a quantum computer that characterizes some particular value in its environment. Like a quantum computer, a state is initialized but instead of applying gates to the state for computation's sake, the state is left to interact with what we want to sense. By performing measurements on the state that's interacted with the object we are sensing, we can determine the value of that object. For example, a quantum sensor exposed to an unknown magnetic field can be used to determine the value of that field. Unlike quantum computing, quantum sensing is a mature technology that's already being used for practical applications. Since the theme of the hackathon was to use quantum computing for social good, it was very difficult to think of a practical application that wasn't decades away from being realized. Brainstorming social good projects for an immature technology is very difficult and we would not have learned how near-term quantum computers can be used to enhance sensing without participating in this hackathon. I hope NYUAD continues to host quantum computing hackathons for social good in the future because these types hackathons foster an environment that encourages students to be creative.
Quantum sensors can potentially be used to detect viruses like COVID faster, cheaper and more accurately than standard methods like RT-PCR tests. A sample is collected from the patient and exposed to a nanodiamond that contains a Nitrogen Vacancy (NV) center. This nanodiamond is coated with a polymer which forms reversible complexes with the viral complementary DNA sequences. Magnetic molecules are incorporated with the complementary DNA sequences to form a pair. The pairs detach from the diamond's surface in the presence of COVID and the interaction of the pair with COVID will create a new compound that will diffuse in the solution. This diffusion will increase the distance between the magnetic molecules and the NV center. The magnetic field the NV center detects becomes weaker the farther the magnetic molecule is from the NV center. This magnetic field can be measured by determining the relaxation (T1) time of the NV center. The weaker the magnetic field, the longer the T1 time. For the hackathon, we simulated the results of a T1 experiment that one would get for a sample that contains COVID and another for when the sample doesn't contain COVID.
The sensitivity of this COVID sensor can be increased with CRISPR technology. The problem is that the sensitivity gained by CRISPR cannot approach fundamental limits of precision allowed by quantum physics. This is where programmable quantum sensors come into play. Variational quantum sensors: quantum sensors augmented by the variational quantum algorithm, can potentially prepare quantum states that achieve the highest sensitivity allowed by quantum mechanics without previous knowledge of the sensing device or its environment. Variational quantum sensing was recently demonstrated on a Trapped ion quantum computer and we will demonstrate it in QvsPY soon. We hope QvsPy will inspire more people to look into how to use near-term quantum computers to improve sensing.
This project wouldn't be possible without NYUAD and the Quantum Sensing Pirates: Ashith Farhan, Chin-Ling Hou, Dania Herzalla, Jakub Nowak, Nouhaila Innan, Pengyu Wang, Sakib Sazzad and Zayd Maradni.
- QvsPy respository
- SARS-CoV-2 Quantum Sensor Based on Nitrogen-Vacancy Centers in Diamond
- Pushing the Limits of Quantum Sensing with Variational Quantum Circuits2s
- Optimal metrology with programmable quantum sensors