Researchers take a step towards turning interactions that normally ruin quantum information into a way of protecting it
A new method for predicting the behavior of quantum devices provides a
crucial tool for real-world applications of quantum technology

Date:
March 8, 2023
Source:
Aalto University
Summary:
A new method for predicting the behavior of quantum devices provides
a crucial tool for real-world applications of quantum technology.


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FULL STORY ========================================================================== Researchers have found a way to predict the behavior of many-body quantum systems coupled to their environment. The work represents a way to protect quantum information in quantum devices, which is crucial for real-world applications of quantum technology.


==========================================================================
In a study published in Physical Review Letters, researchers at Aalto University in Finland and IAS Tsinghua University in China report a
new way to predict how quantum systems, such as groups of particles,
behave when they are connected to the external environment. Usually,
connecting a system such as a quantum computer to its environment creates decoherence and leaks, which ruin any information about what's happening
inside the system. Now, the researchers developed a technique which
turns that problem into its a solution.

The research was carried out by Aalto doctoral researcher Guangze Chen
under the supervision of Professor Jose Lado and in collaboration with
Fei Song from IAS Tsinghua. Their approach combines techniques from two domains, quantum many-body physics and non-Hermitian quantum physics.

Protection from decoherence and leaks One of the most intriguing
and powerful phenomena in quantum systems is many- body quantum
correlations. Understanding these and predicting their behaviour is
vital because they underpin the exotic properties of key components of
quantum computers and quantum sensors. While a lot of progress has been
made in predicting quantum correlations when matter is isolated from its environment, doing so when matter is coupled to its environment has so
far eluded scientists.

In the new study, the team showed that connecting a quantum device to
an external system can be a strength in the right circumstances. When a
quantum device is host to so-called non-Hermitian topology, it leads to robustly protected quantum excitations whose resilience stems from the
very fact that they are open to the environment. These kinds of open
quantum systems can potentially lead to disruptive new strategies for
quantum technologies that harness external coupling to protect information
from decoherence and leaks.

From idealised conditions to the real world The study establishes a
new theoretical method to calculate the correlations between quantum
particles when they are coupled to their environment. 'The method we
developed allows us to solve correlated quantum problems that present dissipation and quantum many-body interactions simultaneously. As a
proof of concept, we demonstrated the methodology for systems with 24 interacting qubits featuring topological excitations,' says Chen.

Professor Lado explains that their approach will help move quantum
research from idealised conditions to real-world applications. 'Predicting
the behavior of correlated quantum matter is one of the critical problems
for the theoretical design of quantum materials and devices. However,
the difficulty of this problem becomes much greater when considering
realistic situations in which quantum systems are coupled to an external environment. Our results represent a step forward in solving this problem, providing a methodology for understanding and predicting both quantum
materials and devices in realistic conditions in quantum technologies,'
he says.

* RELATED_TOPICS
o Matter_&_Energy
# Quantum_Physics # Quantum_Computing # Physics #
Spintronics
o Computers_&_Math
# Quantum_Computers # Computers_and_Internet #
Spintronics_Research # Encryption
* RELATED_TERMS
o Quantum_entanglement o Quantum_number o Quantum_tunnelling
o Virtual_reality o Quantum_dot o Linus_Pauling o
Bose-Einstein_condensate o Quantum_computer

========================================================================== Story Source: Materials provided by Aalto_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Guangze Chen, Fei Song, Jose L. Lado. Topological Spin Excitations
in
Non-Hermitian Spin Chains with a Generalized Kernel Polynomial
Algorithm.

Physical Review Letters, 2023; 130 (10) DOI: 10.1103/
PhysRevLett.130.100401 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230308112210.htm

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