In a quantum system, an experiment reveals the trade-off between measurement and overall information content, which includes gain, disturbance, and reversibility.
According to conventional theory, taking a quantum
measurement permanently alters the system. However, new experiments show that a
post measurement operation can repair a quantum state that has been damaged by
a measurement. Hyang-Tag Lim, Seung-Woo Lee, and its colleagues at the Korea
Institute of Science and Technology in Seoul have developed a method for evaluating
various forms of quantum measurements and determining if the complete
information is maintained [1]. They claim that information about a quantum
state is divided into three components in a measurable connection that varies
depending on measurement strength.
The team employed a photonic qutrit, which is a
three-level quantum system whose states are defined by the travel modes of a
single photon. Optical components, such as angled wave plates and beam
splitters, both prepared and implemented measuring operators for photon states.
The researchers assessed three types of information content during each
measurement: the amount of information gained by the observer about the qutrit
state, the amount of undisturbed information actually transmitted from system to
observer during the measurement, and the likelihood of restoring the
undisturbed state using a reverse operator. The researchers discovered that by
adjusting the strength and types of measurement operators, the amount of each
sort of information tended to vary, with one quantity increasing at the expense
of another. They conclude that the relationship between information and
disturbance can be described as "the more information obtained, the more
the state is disrupted, and the less recoverable it is.
The experiment adds to our knowledge of quantum mechanics' information conservation law and demonstrates how quantum measurements can be adjusted to conserve information. Researchers may be able to develop more trustworthy quantum information technology with the use of such tailored experiments.
References:
- S. Hong et al., “Demonstration of complete information trade-off in quantum measurement,” Phys. Rev. Lett. 128, 050401 (2022).
.jpg)
0 Comments