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.
January in 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.
Is the Moon in the sky when you’re not looking?
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?
How well can we measure position?
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?
Seeing ripples in spacetime
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
Through the looking glass
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 joys of theoretical physics
Have you always thought mathematics is dull and complicated? You are certainly not alone. But there is a lot of beauty hidden in it and in the way it describes our world. Theoretical physics is all about using maths to describe nature. As the universe we live in is vast and filled with myriads of… Continue reading The joys of theoretical physics
How to measure time
Precise timekeeping is crucial for many of our daily activities. High-speed communication (on the internet or in a mobile phone network), satellite navigation, and many other tasks require time synchronisation over long distances to work properly. But how is time measured? And can quantum physics help reach better accuracies? The basic idea behind measuring time is… Continue reading How to measure time
Is nature scared of emptiness?
There can never be a truly empty space. That was the opinion of many scholars from the times of ancient Greece up to the beginning of the twentieth century. When the idea of aether as a medium in which light can travel has been refuted, the existence of vacuum became widely accepted. But then the… Continue reading Is nature scared of emptiness?
How to close an open system
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