Gravitational quantum entanglement simulated

Circuit executed by IBM’s quantum computer, which simulates the creation o
Circuit executed by IBM’s quantum computer, which simulates the creation of quantum entanglement through gravity / Carlos Sabin

A researcher at the Autonomous University of Madrid (UAM) has succeeded in simulating on an IBM quantum computer the creation of quantum entanglement by means of the gravitational field. The work, published in the journal EPJ Quantum Technology, could help in the experimental validation of gravity as a quantum force.

A researcher at the Autonomous University of Madrid (UAM) has carried out a simulation on an IBM quantum computer that could be useful on the road to demonstrating that gravity is a quantum force. Although a real experiment has not yet been performed, this breakthrough is a step towards a better understanding of the quantum nature of gravity.

Published in the journal EPJ Quantum Technology, the study reveals how experimental groups could use these findings to empirically verify the quantum character of the gravitational field.

Carlos Sabín, author of the research, comments: "Although experimental proposals to generate entanglement through gravity are still beyond our current technological capabilities, it is conceivable that this will change in a few years. This development would allow direct verification of the quantum aspects of gravity. In the meantime, I have turned to one of IBM’s quantum computers to simulate these experiments."

Towards a quantum theory of gravity

To date, we do not have a quantum theory of gravity, unlike other fundamental forces such as electromagnetism. Theoretical proposals exist, such as the famous string theory, but their experimental verification remains beyond the reach of current technologies.

Recently, a more modest approach has been developed that aims to simply demonstrate the quantum nature of gravity, without the need to reveal all of the underlying quantum theory. This approach is based on the idea that, if quantum entanglement between systems governed by quantum physics can be generated through purely gravitational means, we could confirm that gravity is, in fact, a quantum force, even without knowing the full theory.

"Entanglement is the term we use to describe certain correlations between measurement results that are only possible in quantum systems. These correlations are extremely useful for the development of new technologies, including quantum computers," explains Sabin.

As part of his research, Sabin translated the results of a specific experiment - carried out by scientists at University College London (UK) and the University of Groningen (The Netherlands) - into the language of quantum bits (cubits) and the transformations between them (quantum logic gates). He then implemented the simulation over the Internet on a quantum computer and analyzed the results, comparing them with theoretical ideals.

"Using modern techniques to ’mitigate’ experimental errors, I have found that the results obtained are practically identical to the theoretical ones. This indicates that the entanglement generated between the cubits would be equivalent to that which would have been generated by gravity between quantum systems in a real experiment," concludes the researcher.

Bibliographic reference:

Sabin, C. (2023). "Digital quantum simulation of quantum gravitational entanglement with IBM quantum computers". EPJ Quantum Technology.­jqt/s40507­’023 -00161-6 .

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