Exploring the various individual properties of a large everyday object is quite simple. However, this becomes much trickier when examining microscopic quantum objects such as photons – tiny tiny particles of light.
So this is because measurements of one property can cause distortions of other properties, as some properties of quantum objects are related. For example, monitoring the position of an electron will change its speed and vice versa.
Such properties are called conjugate properties. This is a direct manifestation of Heisenberg’s famous uncertainty principle: it is impossible to simultaneously measure two conjugate properties of a quantum object with arbitrary accuracy.
Scientists at the Australian National University (ANU) have developed a method to measure small things more accurately using quantum computers. This technique could benefit several future technologies, including biological sensing.
ANU Ph.D. researcher Lorcán Conlon said: “We were able to design a measurement to more accurately determine conjugate properties of quantum objects. Remarkably, our employees were able to implement this measurement in various laboratories around the world.”
“More accurate measurements are crucial and in turn could open up new possibilities for a variety of technologies, including biomedical sensing, laser ranging and quantum communications.”
The new method is based on entanglement, a special property of quantum systems. Scientists noted that monitoring two identical quantum objects when they are entangled allows more accurate determination of properties than measuring them separately.
Co-author Dr. Syed Assad said: “By entangling two identical quantum systems, we can obtain more information. There is some unavoidable noise associated with measuring a property of a quantum system. We can reduce this noise by intertwining the two and get a more accurate measurement.”
According to Professor Ping Koy Lam, A*STAR Principal Quantum Scientist at the Institute of Materials Research and Engineering (IMRE), one of the main strengths of this work is that a quantum enhancement can still be observed in noisy scenarios.
“For practical applications, such as in biomedical measurement, it’s important that we can see a benefit even when the signal is inevitably embedded in a noisy, real-world environment.”
- Conlon, LO, Vogl, T., Marciniak, CD et al. Approaching optimal entanglement of collective measurements on quantum computing platforms. Wet. Physically. (2023). DOI: 10.1038/s41567-022-01875-7