The device used in this work. A square structure close to the center is a superconducting circuit, and a red dot in the center corresponds to the motion of the membrane. The honeycomb structure is used to isolate the movement of the membrane, which occurs mainly in the position of the red dot, from the frame to which it is attached. Credit: Niels Bohr Institute

Researchers from the Niels Bohr Institute at the University of Copenhagen have significantly improved the coherence time of a previously developed quantum membrane. Improvements expand the ability to use membranes for a variety of purposes. With a coherence time of one hundred milliseconds, the membrane can, for example, store sensitive quantum information for further processing in a quantum computer or network. The result is now published in The nature of communication.

The quantum drum is now connected to the reading unit

As a first step, a group of researchers came together membrane with a superconducting microwave circuit that allows accurate readings from the membrane. That is, it has become “connected” as required for virtually any application. Thanks to this design, the membrane can be connected to various other devices that process or transmit quantum information.

Cool the quantum drum system to achieve the quantum ground state

Since the ambient temperature determines the level of random forces that break the membrane, it is necessary to achieve sufficient low temperature to prevent erosion of the quantum state of motion. Researchers are achieving this with a helium-based refrigerator. Using a microwave circuit, they can monitor the quantum state of the membrane. In their recent work, researchers were able to prepare a membrane in a quantum ground state, which means that its motion is dominated by quantum fluctuations. The quantum ground state corresponds to an effective temperature 0.00005 degrees above absolute zero, which is −273.15 ° C.

Applications for the connected quantum membrane set

One could use a slightly modified version of this system that can experience the power of both microwave and optical signals to build a quantum transducer from microwave to optics. Quantum information can be transferred to room temperature in optical fibers per kilometer without perturbations. On the other hand, information is usually processed inside a cooling unit capable of reaching low enough temperatures to operate superconducting circuits such as a membrane. Thus, the connection of these two systems – superconducting circuits with optical fibers – can create a quantum Internet: several quantum computers connected together by optical fibers. No computer has infinite space, so the ability to distribute computing power to connected quantum computers would greatly improve the ability to solve complex problems.

Gravity – not very clear in quantum mechanics, but crucial – can now be explored

The role of gravity in quantum mode is still an unanswered, fundamental question in physics. This is another place where the high coherence time demonstrated here can be applied to research. One hypothesis in this area is that gravity is capable of destroying some quantum states over time. With a device like a membrane, such hypotheses can be tested in the future.

Manipulating the dark states of superconducting circuits in the microwave

Additional information:
Yannick Seis et al., Cooling of an ultracoherent electromechanical system, The nature of communication (2022). DOI: 10.1038 / s41467-022-29115-9

Citation: A quantum drum that stores quantum states for a record long time (2022, May 25), obtained May 25, 2022 from .html

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