Quantum physics has become prevalent across all areas of science in the last few years and is often associated with advances and investments in quantum computing research.
However, much of the investment in quantum technologies is going into “quantum sensing,” which is a growing area of research.
While it is true that quantum computers will bring about improvements in computing power and efficiency in the future, the goal of creating a full-fledged quantum computer is many years away from being achieved.
This is due to the engineering challenges involved: maintaining qubits (the building blocks of a quantum computer) in a quantum state long enough to be usable is extremely difficult, and any external perturbation would cause the system to collapse and become unusable: even tiny variations in properties such as magnetic or electric fields or temperature can cause the quantum state to collapse.
While this sensitivity poses obvious challenges for the development of quantum computers, it can also be harnessed to enable researchers to access interactions and phenomena at a level far beyond the reach of traditional sensing methods.
Today’s quantum sensors have their roots in established technologies such as magnetic resonance imaging (MRI), which are based on similar quantum mechanical principles. In MRI experiments, individual atomic nuclei are used as quantum bits to report information about the surrounding environment. Similarly, most modern quantum sensing uses the “spin” of atomic nuclei or electrons as quantum bits.
As the name suggests, MRI measures how the magnetic field environment around hydrogen nuclei affects their behavior. Modern quantum sensors are often used as highly sensitive magnetic field detectors as well. Unlike MRI, however, quantum sensors often combine magnetic field sensitivity with extremely high spatial resolution, low cost and portability. These properties make them useful across a variety of industries and research fields.
For example, one promising application of quantum sensing is identifying new materials for use in classical computers.
So, you want to study quantum physics?
For classical computers to remain useful into the future, considerations of power consumption and size constraints must be addressed. Electrical engineers are interested in new materials such as graphene and perovskites, which offer advantages over traditional silicon-based devices.
Quantum sensing is helping us understand the magnetic behavior of these new materials, which is a key requirement for selecting materials worthy of further development.
As molecular biology advances, questions regarding the nature of intracellular interactions within individual proteins or between proteins have become targets of fundamental research. Quantum sensors can provide unique information at higher resolution compared to traditional techniques such as optical microscopy.
With this new level of detail, researchers hope that quantum sensing can be used to answer questions that will inform medicine, such as how to design better drugs, the nature of neural signal transmission, and how to more accurately diagnose diseases. These goals are being addressed by the new, seven-year ARC Quantum Biotechnology Center of Excellence.
Quantum sensing has also attracted a lot of attention in the mineral resources field, where it is being used to identify new mineral mining sites using the tiny magnetic fields produced by mineral resources. SQUID magnetometers (Superconducting Quantum Interference Devices) measure the quantized superconducting states. Sensors are already being deployed for this task, and are capable of detecting magnetic fields many times smaller than Earth’s magnetic field.
Finally, given the unique sensitivity of quantum sensors, physicists are also intrigued by the new areas of physics they can access. Quantum sensors could help scientists answer some of the most fundamental questions in physics, such as the nature of dark matter and gravity. A SQUID was recently deployed at the Simons Observatory in Chile to detect the cosmic microwave background radiation (CMB). In this case, instead of a magnetic signal, heat is detected, which is generated when CMB photons hit the SQUID and disturb its quantum state.
