Quantum technologies for inertial sensing

Our society relies heavily on the Global Positioning System (GPS) to facilitate the supply lines that support our economy, to enable the movement of goods and people in unfamiliar places, to help maintain power networks, and support our emergency services and military. GPS works by sending signals from a network of satellites orbiting the earth 20,000km above our heads to receivers on Earth, which can determine position with an accuracy of a few metres. However, GPS does not provide a fail-safe system for determining position. It doesn't work under ground or under water and because it relies on signals being sent from space to receivers in our phones, cars or other sat-nav enabled devices, it's vulnerable to local weather conditions, spoofing and being blocked. To overcome the vulnerabilities of GPS I'm going to develop a new type of location service that harnesses quantum physics to determine position without the need to send or receive signals to someone else. Instead of using a network of satellites orbiting the earth in order to navigate, I am going to use electron orbitals in clouds of atoms.

Atoms make very good sensors because each atom of a particular element is identical. This means that atomic sensors all behave in the same way no matter what their local environment. They come pre-calibrated, so different sensors will always agree with one another, and unlike electronic devices they do not age or wear out over time. However, in order to describe the behavior of atomic sensors we need to use quantum mechanics.

According to quantum mechanics particles such as electrons, atoms and even molecules behave like waves that can explore extended areas of space and can even be in two places at once - called a quantum superposition. Quantum superpositions are extremely fragile, which is why we don't observe them in our everyday lives. However, by cooling atoms down to extremely low temperatures and storing them inside a protective apparatus we can create an environment where they be can preserved, and even used to our advantage.

My new location device works by placing a cloud of atoms in a superposition using carefully controlled pulses of laser light. If the protective chamber housing the cloud of atoms is moving then the superposition will be disturbed very slightly, and the electron orbitals in the atoms will change. When this happens the amount of light that the atoms can absorb will also change, and by an amount that depends only on how fast the protective chamber is moving. If we measure very precisely how much light the atoms absorb over time, we can calculate how the vehicle carrying them is moving and how therefore how far it has moved. As long as you know where you were you were when you first started measuring, you'll always then know where you are and all without ever having to send a signal to anyone else.