Researchers from MIT, Caltech, Harvard University and other institutions have transported quantum information across a quantum system for the first time, in a process that can be compared to going through a wormhole. Calculations from the experiment showed that qubits moved from one system of entangled particles to another in a gravitational pattern, but this experiment did not create a disruption in physical space and time in the sense in which we can understand the term "wormhole" from science fiction. This experiment used the Sycamore quantum processor device from Google, which paves the way for more quantum computing research on gravitational physics and string theory in the future.

One of the most fascinating uses for quantum computers is the simulation of strongly interacting quantum systems, such as those that arise in quantum gravity, according to Daniel Harlow, Associate Professor of Physics for Career Development and a researcher at the MIT Nuclear Science Laboratory (LNS). Harlow is working with David Kolchemeyer, one of the study's lead authors. “This is a positive first step.”

In a new publication published in Nature, researchers Kolchmeyer and Alexander Zlokapa, from the MIT Center for Theoretical Physics (CTP) and LNS, describe the findings of two quantum systems that behave similarly to a traversable wormhole.

A wormhole connects two distant regions of spacetime. According to the general theory of relativity, nothing is allowed to pass through the wormhole. In 2019, Harvard University's Daniel Jafferis and colleagues suggested that an entangled black hole could create a wormhole through which one could pass.

Using a simple quantum dynamic system made up of fermions, these scientists "found a quantum mechanism for making a wormhole traversable by providing a direct interaction between regions of distant space-time," Kolchmeyer explains. We used these entangled quantum systems in our effort to create this kind of "wormhole teleportation" using quantum computing and were able to verify the results using conventional computers.

The study, with senior authors Professor Maria Spiropulu and Jafferis of Caltech, published Dec. 1 in the journal Nature. Lead authors include Joseph D. Lykken of the Fermilab Quantum Institute and Department of Theoretical Physics, Kolchmeyer and Zlokapa of MIT, and Hartmut Neven of Google Quantum AI. Samantha I. Davis and Nikolai Lauk are two other contributing researchers from Caltech and the Alliance for Quantum Technologies (AQT).

In this experiment, scientists used the Sycamore 53-qubit quantum processor to move a quantum state from one quantum system to another to send a signal through the "wormhole." The work team had to find entangled quantum systems that behaved as predicted by quantum gravity and were also small enough to run on current-generation quantum computers.

According to Zlokapa, a sophomore physics graduate student at MIT who began this research as an undergraduate in Spiropulu's group, the main challenge in this work was to define a sufficiently simple multibody quantum system that retains gravitational properties.

To achieve this, scientists used machine learning approaches to steadily reduce the connectivity of highly interacting quantum systems. Each sample of systems with quantum gravity-consistent behavior that emerged from this learning process required only about 10 qubits, making it the ideal size for the Sycamore processor.

Finding such small samples was crucial, according to Zlokapa, as larger systems with hundreds of qubits wouldn't be able to run on the quantum platforms currently in use.

After Zlokapa and his team found these 10-qubit systems, they were able to display the same information in the other quantum system in the processor by placing a qubit in one system and then applying a shock wave of energy through the processor. Depending on whether a positive or negative shock wave was delivered, the scientists measured how much quantum information was transferred between the two quantum systems.

“We have shown that if the wormhole is kept open by negative energy shock waves for a sufficient time, a causal path can be constructed between two quantum systems. According to Spiropulu, the qubit inserted into one system is indeed the same qubit that appears in the other system.

The scientists then used conventional computer calculations to verify these and other features. According to Spiropulu, “this is different from simulating on a conventional computer.” No physical system, even simulated on a classical computer, is created through a conventional simulation, which is the classical manipulation of bits, zeros, and ones, and this has been done as detailed in this study. Here we observed how the data went through the wormhole.

Thanks to this new research, future quantum gravity experiments with larger quantum computers and more complex entangled systems are now possible. According to Spiropulu, this research does not replace direct observations of quantum gravity, as the Laser Interferometer Gravitational-Wave Observatory (LIGOdiscovery) has obtained from gravitational waves.

Kolchmeyer and Zlokapa are interested in learning how these experiments can increase our understanding of quantum gravity. “I'm very interested in seeing how far we can investigate quantum gravity in today's quantum computers. I'm pretty excited about some of our special follow-up work ideas,” adds Zlokapa.

source: news.mit.edu

📩 13/12/2022 23:19

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