2021-11-15

Adding sound to quantum simulations: scientists create an atomic optical lattice that can vibrate

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f2c2c434b8e3042 - Adding sound to quantum simulations: scientists create an atomic optical lattice that can vibrate

when sound was first incorporated into films in the 1920s, it brought new possibilities to film makers, such as music and oral dialogue. Physicists may be about to usher in a similar revolution, thanks to a new device developed by Stanford University, which is expected to bring sound to previously silent quantum science experiments

in particular, it can bring sound to a common Quantum Science device called an optical lattice, which uses a crisscross network of laser beams to orderly arrange atoms in a crystal like manner. This tool is usually used to study the basic characteristics of solid and other material stages with repeated geometry. However, one disadvantage of these lattices is that they are silent

Benjamin LEV, associate professor of Applied Physics and physics, said: “if there is no sound or vibration, we will miss a key degree of freedom existing in real materials.” he focused on this problem when he first came to Stanford University in 2011. “It’s like forgetting to put salt in soup. It will really make the taste of quantum’soup’ disappear.”

3810afb1dad10b2 - Adding sound to quantum simulations: scientists create an atomic optical lattice that can vibrate

after ten years of engineering and benchmarking, Lev and collaborators from Pennsylvania State University and St Andrews University have created the first atomic optical lattice containing sound. The study was published in the journal Nature on November 10. By designing a very precise cavity and placing the lattice between two highly reflective mirrors, the researchers enabled atoms to “see” themselves repeated thousands of times through photons bouncing back and forth between the mirrors. This feedback makes photons behave like phonons, the building blocks of sound

Lev said: “if it is possible to put your ears on the atomic optical lattice, you will hear their vibration at about 1 kHz.

previous optical lattice experiments are silent because they lack the special elasticity of this new system. LEV, young graduate student Sarang Gopalakrishnan (now assistant professor of physics and co-author of the paper at Pennsylvania State University) and Paul goldbart (now provost of Stony Brook University) The basic theory of this system was put forward. However, with the cooperation of Jonathan keelin, a reader of St. Andrews University and co-author of the paper, the corresponding device was established after years of efforts.

in order to create this device, researchers filled an empty mirror cavity with an ultra cold rubidium atomic quantum gas. In itself, this is a superfluid and a substance A phase of matter in which atoms can rotate and flow without resistance. When exposed to light, the superfluid of rubidium will spontaneously rearrange into a super solid – a rare material phase, showing the order in the crystal and the extraordinary fluidity of superfluid.

what brings sound to the cavity is the carefully spaced concave mirrors on both sides, whose reflectivity is so high that There is a one percent chance that a photon will pass through them. This reflectivity and the specific geometry of the setting — the radius of the curved mirror is equal to the distance between them — cause photons pumped into the cavity to pass through atoms more than 10000 times. In doing so, photons form a special close combination with atoms, forcing them to arrange into a lattice.

“ The cavity we use provides more flexibility in the shape of the light bouncing back and forth between mirrors, “Lev said.” it’s like, instead of just allowing a single wave to be made in the tank, you can now splash it freely and make any kind of wave. ”

this special cavity allows superfluid atomic lattice (supersolid) Moving, so, unlike other optical lattices, when poked, it can deform freely — which produces sound waves. In order to start this phonon emission through the flexible lattice, the researchers poked it using an instrument called a spatial light modulator, which allows them to program different patterns in the light injected into the cavity.

the researchers capture the emitted light The hologram of light is used to evaluate the impact on the cavity content. The hologram records the amplitude and phase of light waves at the same time, allowing the imaging of phonons. In addition to mediating interesting physics, the high curvature of the mirror in the device produces a high-resolution image, just like a display mirror, which makes researchers name their creation “active quantum gas microscope” Yudan Guo, a graduate student and lead author who won the q-farm scholarship to support this work, led the efforts to confirm the existence of phonons in the device by sending different modes of light, measuring things and comparing them with the Goldstone dispersion curve, which shows how energy, including sound, moves in the crystal; their discovery Matching this curve, this confirms the existence of phonon and vibrational ultrasolids.

Lev hopes that his laboratory — and perhaps others — will push the invention in many directions, including studying the physics of strange superconductors and creating quantum neural networks — which is why the team has been working to create a second version of their device.

Lev said: “If you open a typical textbook of solid-state physics, you will see that a large part is related to phonons. Moreover, until now, we can’t study anything based on this with quantum simulators using atoms and photons, because we can’t simulate this basic form of sound.”