A global protocol that flips qubit evolution with a high probability of success

Researchers at the Institute of Quantum Optics and Quantum Information (IQOQI) in Vienna have recently devised a universal mechanism to reverse the evolution of qubits with a high probability of success. This protocol, described in Physical review lettersit can return any target qubit to the state it was in at a specified time in the past.

The introduction of this protocol depends on previous paper Published in 2020, the same team presented a series of temporal translation protocols that can be applied in unsupervised settings. While some of these protocols have been promising, in most of the scenarios tested, their probability of success turned out to be very small. In their new study, the researchers set out to create an alternative protocol with a higher probability of success.

“Our newly developed protocol reverses the single-qubit evolution,” David Trillo, one of the researchers who conducted the study with Benjamin Dive and Miguel Navascués, told Phys.org. A qubit (or qubit) is a two-level quantum system that acts as the quantum equivalent of the qubits used in quantum computers. Any quantum system has some natural evolution in time that needs to be controlled or at least computed when designing the processes around them (eg, When building a quantum computer). Our protocol takes a qubit and outputs the same system, but in the state it would be in if it had evolved backwards in time.”

The protocol created by Trillo and colleagues is universal, meaning that it can be applied to any qubit, regardless of its natural time evolution or the state it is in when the protocol is used. Global protocols are probabilistic in nature, which means that they cannot succeed all the time, rather they have a certain probability of success.

In initial evaluations, the researchers found that the global quantum rewinding mechanism has a high probability of success, i.e. 1. Essentially, the protocol works by setting a target qubit on an overlay of flight paths and then performing a series of quantum operations on it. .

“Our protocol works with unsupervised systems, or in other words qubits to which we don’t know how to apply certain transformations,” Trillo explained. “The cool new feature is that when it fails, we can patch the failure and nudge the system into the desired state. By making these patches adaptively, we can make the probability of success as high as we want it to be, at the cost of increasing the uptime of the protocol.”

The new universal protocol presented by Trillo and colleagues allows researchers to return any given qubit in an unsupervised environment with a high probability of success. While protocols that can achieve this in controlled settings already exist, unlocking the ability to propagate individual qubits in unsupervised environments to an earlier state could open up new valuable possibilities for research.

“One wonders what other phenomena from the controlled setting we can transfer to the unsupervised environment,” Trillo added. “Ideally, we would like to generalize this protocol to higher dimensional systems. However, this appears to be a major challenge, as new ideas are required for this. We are also looking to improve the success potential of the other protocols in the original paper, especially the SWAP protocols” .

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