Light pulses can be saved and retrieved in the glass cell, which is filled with rubidium atoms and is only a couple of millimeters in size. Credit: © University of Basel, Department of Physics/ScixelResearchers at the University of Basel have actually built a quantum memory component based on atoms in a tiny glass cell. In the future, such quantum memories could be mass-produced on a wafer.It is tough to picture our lives without networks such as the internet or smart phone networks. In the future, comparable networks are planned for quantum innovations that will allow the tap-proof transmission of messages using quantum cryptography and make it possible to link quantum computer systems to each other.Like their conventional counterparts, such quantum networks need memory components in which information can be temporarily saved and routed as needed. A team of researchers at the University of Basel led by Professor Philipp Treutlein has now developed such a memory aspect, which can be micro-fabricated and is, therefore, appropriate for mass production. Their results were recently released in the clinical journal Physical Review Letters.Photon storage in glass cellsLight particles are particularly suited to transmitting quantum information. Photons can be utilized to send out quantum details through fiber optic cables, to satellites or into a quantum memory aspect. There, the quantum mechanical state of the photons has actually to be saved as specifically as possible and, after a certain time, converted back into photons.Two years earlier, the Basel researchers showed this works well using rubidium atoms in a glass cell. “However, that glass cell was several and handmade centimeters in size,” states postdoc Dr. Roberto Mottola: “To be appropriate for daily use, such cells need to be smaller and open to being produced in great deals.” That is specifically what Treutlein and his partners have now accomplished. To use a much smaller sized cell determining just a few millimeters, which they obtained from the mass production of atomic clocks, they needed to establish a few tricks. In order to have a sufficient number of rubidium atoms for quantum storage regardless of the small size of the cell, they had to warm up the cell to 100 degrees centigrade to increase the vapor pressure.Moreover, they exposed the atoms to a magnetic field of 1 tesla, more than 10 thousand times more powerful than Earths electromagnetic field. This moved the atomic energy levels in a method that facilitated the quantum storage of photons utilizing an additional laser beam. This approach enabled the scientists to store photons for around 100 nanoseconds. Free photons would have traveled 30 meters because time.A thousand quantum memories on a single wafer” In this way, we have developed, for the very first time, a miniature quantum memory for photons of which around 1000 copies can be produced in parallel on a single wafer”, states Treutlein. In the existing experiment, storage was demonstrated utilizing highly attenuated laser pulses, but in the future, Treutlein, in collaboration with the CSEM in Neuchatel, likewise wishes to save single photons in the miniature cells. Additionally, the format of the glass cells still requires to be optimized, such as to keep the photons for as long as possible while protecting their quantum states.Reference: “Optical Memory in a Microfabricated Rubidium Vapor Cell” by Roberto Mottola, Gianni Buser and Philipp Treutlein, 26 December 2023, Physical Review Letters.DOI: 10.1103/ PhysRevLett.131.260801.
In the future, similar networks are prepared for quantum technologies that will allow the tap-proof transmission of messages utilizing quantum cryptography and make it possible to connect quantum computer systems to each other.Like their traditional counterparts, such quantum networks need memory elements in which info can be momentarily kept and routed as needed. Photons can be used to send quantum info through fiber optic cable televisions, to satellites or into a quantum memory element. Free photons would have taken a trip 30 meters in that time.A thousand quantum memories on a single wafer” In this method, we have developed, for the very first time, a miniature quantum memory for photons of which around 1000 copies can be produced in parallel on a single wafer”, states Treutlein.
