Quantum Sensors: Small Atoms Changing the World

In our large macroscopic world, the smallest unit we can think of would be in the particle realm. Even if we zoom in a thousand times into the microscopic world, for decades, researchers believed that a particle would be and act like just that, a simple particle.

However, in this microscopic world, quantum science introduces the idea that small objects have far greater potential and depth than researchers have ever discovered. Small objects can act as both particles and waves, which could have the potential to revolutionize the way we see and interact with them. This duality introduces pivotal characteristics that can be used to create cutting-edge technology. This includes quantum sensors; today’s topic.

However, introductions are in order. The word quantum refers to the minimum amount of any physical entity involved in an interaction. Going into technicalities, quantum is a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents. The fundamental notion that any property can be quantized is referred to as the “hypothesis of quantization.” 

Quantum sensors can sense, or detect, small changes in external factors. These changes are detected by exploiting the fragility, sensitivity and size of quantum states. In these systems, particles can maintai quantum superposition; the scientific way of saying these particles have properties that coexist simultaneously as a distribution of various parameters. These distributions are affected when external factors such as time, temperature, pressure, frequency, and acceleration change. The change in these distributions can be preserved with great precision by quantum sensors due to their small size and thus sensitivity. For example, if we change a parameter; say a human is walking and then walks faster (accelerates), the quantum sensors of that human's body will be affected, and that too by a lot. Because they're so small and react considerably to external factors, analyzing quantum sensors can help researchers build precise conclusions about what they're studying; in this case the relationship between the human body and increasing walking pace.

A relevant application of quantum sensors that I’ve researched is (predictably) in the field of biomedicine. In this field, two forms of quantum sensors (optically pumped atomic magnetometers - OPM) and (nitrogen-vacancy centers - NV) utilize spin: a particle’s angular momentum for quantum sensing of cell anomalies. 

Additionally, quantum sensors detect tiny magnetic fields generated by the brain, offering high-resolution imaging for neurological studies (magnetoencephalography). Quantum-enhanced magnetic resonance imaging (MRI) provides better neurological diagnostics with lower magnetic field strengths. 

But medicine and biotechnology isn’t the only field where quantum sensors are making strides. They’re already employed in so many fields; for example, atomic clocks which are the most precise timekeeping devices, essential for GPS and global navigation. Quantum sensors can also detect tiny deviations in physical constants or forces, helping scientists explore fundamental questions about the universe, such as dark matter or gravitational waves which enable mapping of underground structures, water levels, and mineral deposits. 

Quantum sensors can also enable the development of computational quantum networks, supporting secure communication through quantum key distribution and improving synchronization in distributed systems. Sensors integrated with quantum networks will enhance data transfer and computational precision, because any cybersecurity attacks or computational anomalies can be immediately and precisely quantified (and sometimes even located).

In conclusion, quantum sensors hold vast potential to revolutionize so many fields, including world mapping, physics, computer science; and of course, medicine. Their small size promotes precision and accuracy that very few technologies have. I hope you enjoyed reading this article, learned something new about quantum sensors (and also perhaps why bigger isn’t always better, since the small size of quantum sensors is the reason they're so groundbreaking), and I’ll see you in the next blog post!