INESC TEC researchers developed a study to test the ability to perform any Boolean function on quantum computers designed according to a measurement-based quantum computation model.
Readers may not know about this, but the device on which they are reading this news features a computation process named Boolean function — capable of solving binary questions, like whether a password is correct or not. But are Boolean functions feasible in quantum computers, designed according to a measurement-based quantum computation model?
Currently, most quantum computers – even those used by large companies – are based on the circuit model. However, the measurement-based quantum computation model has as the main differentiating factor that it does not carry out the computations by performing logic gates on quantum bits, but rather through an initial process that entangles all the quantum bits necessary for the computation – and, subsequently, obtains the results through sequential and adaptive measurements on the same quantum bits.
In this sense, Michael Oliveira and co-author Luís Soares Barbosa, researchers at INESC TEC, dedicated themselves to developing methods for determining and compiling quantum circuits for measurement-based models. To ascertain the results, they focused on the evaluation of Boolean functions. In the paper Quantum advantage in temporally flat measurement-based quantum computation — published in the Quantum Journal, and presented at the Asian Quantum Information Science conference — the researcher focuses on the description of said computations and demonstrates that, at least for one of the subclasses, there is a quantum advantage.
According to Michael Oliveira, “to proceed with this evaluation, it is necessary to identify which states and measures are essential to obtain the desired response while processing the results of these measurements. This was previously known; however, the method for performing these computations, with the correct measurements to perform, was unknown. This research also focused on the comparison between these computations and classical computations in terms of efficiency. For example, to assess the fastest and more efficient manner to perform the calculations.
This model, according to the researcher, has already proved useful to facilitate the understanding of quantum advantages. “This model is intrinsically linked to quantum states and resources inaccessible to classical computers. One requires adaptive measurements to unlock its full potential”. These measurements start by creating a quantum state, moving on to the measurement of some qubits and waiting for the results to subsequently measure the following ones.
However, this process shows several constraints, namely the preservation of stable quantum states after the first sequence of measurements. One solution explored were computation alternatives that did not require this criterion. So, the researchers studied what can be calculated with the resources available in contemporary laboratories, where computations are carried out.
“This work is part of a series of studies that seek to answer one of the fundamental questions of quantum computing: what kind of computations do quantum computers excel at”. “The most notorious example is the ability to decipher classic codes, which threatens the security of digital communications”, explained Michael Oliveira. There may also be a significant computational advantage in the simulation of chemical processes — which could revolutionise the development of new drugs.
Doubts about the benefits of quantum computers still apply to many issues. As such, proving the existence of an advantage for a broad spectrum of computations, like Boolean functions, is an ambitious goal that would allow researchers to claim, for example, that “quantum computers bring benefits to almost all our computational applications”.
The researchers mentioned in this news piece are associated with INESC TEC and UMinho.
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