A child on a swing can keep the swing in motion by repeatedly standing up and squatting down. This movement changes the frequency of the swings and amplifies them. This simple concept—known as parametric amplification—finds use also in modern quantum physics.
The beginning of the year was filled with great physics. Lots of interesting theory has been done, including by me (but more details on that later). But today I want to talk about three experiments that push our abilities to control matter using light into new regimes. In two of them, scientists were able to observe quantum effects in the motion of levitated objects for the first time. In the third one, the authors used their incredible control of single atoms to create a very thin and light mirror.
If you find quantum physics hard to understand (or accept), rest assured that you are not alone. Even many physicists (including Albert Einstein, one of its founding fathers) refused to acknowledge that our world can behave so strangely. That atoms or electrons can be at two places at once or that it does not always… Continue reading Is the Moon in the sky when you’re not looking?
It is a well-known fact in quantum physics that the position and momentum of an object (e.g., a single atom or a vibrating mirror) cannot be known with an arbitrary precision. The more we know about the position of a mirror, the less we know about how fast it is moving and vice versa. This… Continue reading How well can we measure position?
One hundred years after Albert Einstein shared it with the world, the general relativity is waiting for its last confirmation: direct observation of gravitational waves. These ripples in the curvature of spacetime are created when a massive object accelerates. Typical examples of such systems are binary neutron stars or black holes; as the two stars (or… Continue reading Seeing ripples in spacetime
Entanglement is a peculiar feature of quantum systems that makes them behave as if they were sitting directly next to each other even if they are kilometres away. Such behaviour does not occur in classical physics. Classical particles can affect each other through fields -- such as the gravitational or electromagnetic field -- but these fields propagate with… Continue reading Connecting superconducting quantum computers with light
One of the things I love about physics is how it changes the way one sees the world. As one starts to think about some basic things very differently. Then even such a simple act as measurement is a complicated process which can even be used to manipulate physical systems.
The basic picture of an optomechanical system, that even many scientists keep in mind, is that of a cavity with one movable mirror. But that is not the only way to achieve coupling between light and mechanical vibrations. Every time light is strong enough (and the mechanical oscillator light enough), the light can be used to… Continue reading Wi-Fi for a quantum computer
When students encounter quantum physics for the first time, it is as simple as it gets -- there are no unwanted interactions, no noise, particles do not get lost. In the real world, nothing is so easy, though. Take a single atom placed in an optical cavity, for instance. (The cavity helps to enhance the… Continue reading How to close an open system
Using light, we can achieve more than simply see the world around us. Spectroscopy can be used to find chemical composition of a sample, frequency of light interacting with atoms can be used to measure time. We can even move objects by shining light at them. Such manipulations are far from tractor beams of science fiction, but optical tweezers are commonly used to manipulate small objects in many labs around the world. And there are other ways how to control matter using light.