A team of researchers at the Australian National University (ANU) has laid out a method for achieving more accurate measurements of microscopic objects using quantum computers. The research could prove useful across a wide range of next-generation technologies, including biomedical sensing.
While examining the various individual properties of a large everyday object like a car is simple (owing to its well-defined position, colour and speed), measuring a microscopic quantum object like a photon is much harder. This is because certain properties of quantum objects are connected and measuring one property can disturb another property. For example, measuring the position of an electron will affect its speed and vice versa.
These properties are known as conjugate properties. They are a direct manifestation of Heisenberg’s famous uncertainty principle – it is not possible to simultaneously measure two conjugate properties of a quantum object with arbitrary accuracy.
Lead author and ANU PhD researcher Lorcán Conlon noted that this one of the defining challenges of quantum mechanics. He said that the team was able to design a measurement to determine conjugate properties of quantum objects more accurately. Moreover, their collaborators were able to implement this measurement in various labs around the world.
More accurate measurements are crucial, and can in turn open up new possibilities for all sorts of technologies, including biomedical sensing, laser ranging, and quantum communications, he added.
The new technique revolves around a strange quirk of quantum systems, known as entanglement. According to the researchers, by entangling two identical quantum objects and measuring them together, scientists can determine their properties more precisely than if they were measured individually.
Dr Syed Assad, a co-author on the project, noted that by entangling two identical quantum systems, researchers acquire more information. There is some unavoidable noise associated with measuring any property of a quantum system. By entangling the two, this noise can be reduced and a more accurate measurement can be obtained.
Theoretically, it is possible to entangle and measure three or more quantum systems to achieve even better precision, but in this case the experiments failed to agree with the theory. Nevertheless, the authors are confident that future quantum computers will be able to overcome these limitations.
Mr Conlon stated that quantum computers with error-corrected qubits will be able to gainfully measure with more and more copies in the future.
According to Professor Ping Koy Lam, A*STAR chief quantum scientist at Institute of Materials Research and Engineering (IMRE), one of the key strengths of this work is that a quantum-enhancement can still be observed in noisy scenarios. He said that for practical applications, such as in biomedical measurements, it is important that we can see an advantage even when the signal is inevitably embedded in a noisy real-world environment.
The study was conducted by experts at the ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), in collaboration with researchers from A*STAR’s Institute of Materials Research and Engineering (IMRE), the University of Jena, the University of Innsbruck, and Macquarie University. Research and architectural support was provided by a leading IT service management company and made the Rigetti Aspen-9 device that uses the company’s fully managed quantum computing service.
The researchers tested their theory on 19 different quantum computers, across three different platforms: superconducting, trapped ion and photonic quantum computers. These world leading devices are located across Europe and America and are cloud-accessible, allowing researchers from across the globe to connect and carry out important research.
Source: https://www.anu.edu.au/news/all-news/new-techniques-for-accurate-measurements-of-tiny-objects
