By using natural signals, researchers at Chalmers University of Technology in Sweden have discovered a way to control and communicate (Harnessing the power of symmetry for new quantum technologies) with the dark state of atoms. This research opens another way to build quantum computing networks and quantum sensors to detect dark matter in the universe.
“Nature loves symmetries and we love them. The basis of our experiments is a new engineering trick where we manage and use symmetries in systems that are difficult to tame,” technical researcher and leader Dr. Aamir Ali said.
Quantum computers may surpass today’s most advanced computers. A quantum computer is based on so-called quantum bits, or qubits, which can be in all of its possible states, 0 and 1, at the same time. This phenomenon allows quantum computers to handle large amounts of data. However, the cover is not very strong, which means that it must be protected from external problems to prevent them from collapsing.
Therefore building a large quantum computer presents a great challenge, as the number of qubits increases, the computational process becomes more complex. For this reason, the main research area is the development of large quantum networks where the processing tasks are organized and distributed across different parts of the network. An interesting way to understand such networks is to use artificial atoms* as qubits. Atoms interact with light, absorbing or emitting photons. However, two or more tentacles can exist in a special state of superposition, called the dark state, in which they are completely transparent to light, that is, they do not emit or transmit. . These dark states have great potential in quantum technology because they are insensitive to external perturbations. For one reason, controlling dark states and using them to exchange information is a difficult task.
Pay attention to the small symmetry of the atom
Now, researchers at the Chalmers University of Technology have developed a simple and highly advanced method (Harnessing the power of symmetry for new quantum technologies) to control the dark state of a single molecule consisting of two artificial atoms bonded together. The study was published in Physical Review Letters.
From butterfly wings and snowflakes to the tiniest part of our physical world, nature seeks expression to create balance and harmony. This is also true for energy levels in atoms. The qubits used by Aamir Ali and his colleagues consist of two atoms connected together by an efficient circuit**. When light particles – photons – are sent into the atom by wave conversion ***, they can interact with energy levels of two different symmetries. In previous research, a pair of waves connected to a qubit had a small chance of getting its signal, but the Chalmers researchers used two pairs of ships, each associated with a single symmetric state. Due to the symmetric distribution of energy in active atoms, one of the oscillators will be connected to the dark state and the other to the supporting light state. This allows them to be manipulated and controlled independently.
New applications in quantum technology
This ability to control the dark state provides a new framework for applications in quantum technology. Using Chalmers’ research engineering, it is possible to create a **** connection between the dark state and the light state, which opens up new ways to process quantum information and transmit it in quantum networks. Furthermore, it allows the development of sensors capable of absorbing low-energy microwave photons. A photon detector in this area could contribute to the detection of dark matter in the Universe. The researchers will also use these new results in thermodynamics to see if the laws of quantum mechanics can be used to advantage in motors or batteries.
“We can design synthetic molecules with unique symmetry, which leads to new ways for these molecules to interact with microwave light. Our concepts have proven to be both elegant and powerful, with applications ranging from distributed quantum computing to microwave photodetectors. Says Professor Simone Gasparinetti, head of research and experimental Quantum Physics and one of the main authors of the study.
The research was carried out at Chalmers as part of the Wallenberg Center for Quantum Technology (WACQT), a comprehensive research program with the aim of bringing together Swedish research and industry leaders in quantum technology.
“One of the goals of WACQT is to build a quantum computer, but there’s a lot more to it. We have created an environment that encourages researchers to explore non-travelling routes while benefiting from resources and expertise in quantum technology, this project is an example of this,” says Simone Gasparinetti .
How it works
Artificial atoms are electronic circuits that, like real atoms, can only occupy a certain energy level – unique. When combined with the two waveguides, they create a shared structure that uses quantum interference to connect the waveguides in two different symmetries that the energy levels of atoms can assume. Thanks to this connection and symmetry, it is easy to choose and simply create a dynamic change. This can be done more easily and efficiently than previously shown, without the need to use sophisticated methods and lighting control, which is common in architecture.
Explanation of words
- * Artificial Atom: A small functional element that retains charge and energy like a real atom. But like a real atom, it changes state by emitting or absorbing light at the same time. The artificial atoms used by the Chalmers researchers are highly efficient circuits that convert light at microwave frequencies.
- ** Superconductivity: the property of certain materials that conduct electricity and become incapacitated when cooled below critical temperatures.
- *** Wave Guide: The structure that carries photons and microwave signals
- **** Summary: Phenomenon won the Nobel Prize in Physics in 2022. When the objects are linked, a change in one of the objects will also cause the behavior of the other objects to change, regardless of the distance between them.
