Researchers from the AWS Center for Quantum Networks and Harvard University have presented quantum memory on the
In quantum networks, information is transmitted usingentangled quantum bits or qubits, the scientists explain. Quantum memory is a small quantum computer that can capture and store quantum bits encoded in photons without measuring them. Any impact will destroy the entanglement, while the qubits in quantum memory can be processed and recoded if necessary.
In their work, scientists used technology,which is called the center of silicon vacancies. These are quantum bits made up of electrons around individual silicon atoms embedded in diamond crystals. The silicon vacancy is embedded in a patterned diamond wire that guides photons towards it. Depending on the quantum state of the electron, photons are reflected in different ways, which makes it possible to store quantum information in the spin of the electron.
Our system resembles optical modulators,which carry most of the Internet traffic. Like optical modulators, our quantum memories are switches that either let light through or reflect light depending on whether they are “on” or “off.” Unlike conventional modulators, ours are turned on and off by a single electron, not by large electrical signals, and can be in a quantum superposition of on and off.
David Levonian, study co-author in an interview with Phys.org
A) Quantum levels of the center of silicon vacancies indiamond. Electrical control pulses "MW" and "RF" can switch the magnetic spins of nuclei and electrons up and down. B) and C) Image of the device under an electron microscope. The silicon vacancy is embedded in a patterned diamond wire that guides photons towards it. Image: Stas et al., Science
Electronic spins are very convenient for interactionwith photons, but are also sensitive to magnetic and electric fields, the researchers note. This sensitivity reduces the time of their coherence (conservation of the quantum state). To solve this problem, researchers have developed a technology to transfer quantum information from electrons to more inert nuclear spins.
In a series of experiments, scientists have shown thatthe memory can operate at 4K (rather than 0.1K like previous systems) and still retain information for a relatively long time. The authors of the work note that even such a seemingly insignificant change in the temperature at which the memory module operates reduces cooling costs by an order of magnitude.
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