Quantum microscopy and biosensing

Quantum optical precision sensing techniques are translated to biological measurements, maximizing measurement precision and minimizing biological sample damage.

Biology is a longstanding frontier for quantum metrology, where high optical intensities are frequently required to get sufficient signal, but lead to damage in the biological sample. Quantum optics based precision measurements allow getting the most signal with the lowest optical power. Therefore Queensland Quantum Optics Laboratory aims to translate the precision sensing techniques from quantum optics to biological measurements. This philosophy has recently been very successful in astronomy, allowing the LIGO collaboration to detect the first gravitational waves. Optical tweezers is a common tool in biological experiments that allow manipulation and tracking of single cells and small glass spheres in a live biological sample. Here in Queensland Quantum Optics Laboratory we have used the quantum optics philosophy to demonstrate tighter trapping in optical tweezers [1] and the first quantum enhanced measurement in biology [2].

Single molecule biosensors are designed to make measurement on biological processes which are too small to be seen in a normal microscope. We have developed the first quantum noise limited biosensor allowing us to detect and track single proteins down to 5 nanometre in size and track them with 1000 measurements per second [3]. Notably this is achieved using only a tiny fraction (1E-4) of power compared to other sensors, and thereby greatly reduces photodamage. We aim to use this sensor to uncover biological phenomena never directly seen before, such as the rotational steps of single motor molecules.

The above biosensor and several of our other experiments are based on optical nanofibres. We have developed unique fabrication methods including precision characterisation that can measure the nanofibre thickness with sub-nanameter resolution [4]. Raman microscopy allows measurement on biological samples where not only the contrast of the sample, but also the chemical composition is visible. However, measurements are generally slow and require a lot of power, which can damage the samples. To overcome these challenges we are developing the first quantum enhanced stimulated Raman microscope.

Australian Research Council
Air Force Office of Scientific Research
ARC Centre of Excellence for Engineered Quantum Systems