Biological Measurement Beyond the Quantum Limit

Michael A. Taylor, Jiří Janoušek, Vincent R. Daria +4 more

Michael A. Taylor, Jiří Janoušek, Vincent R. Daria +4 more

Quantum metrology allows high sensitivity measurements to proceed with a lower light intensity than classically possible [1]. An important frontier for this technology is in biological measurements, where photochemical interactions often disturb biological processes and can damage the specimen [2]. Here we report the first demonstration of biological measurement with precision surpassing the quantum noise limit [3]. This was enabled through the development of a new microscopy system which extended previous methods used to track the motion of highly reflective mirrors with non-classical light to measurements of microscopic particles with non-paraxial fields (see Fig. 1). Biological dynamics in the critical Hz-kHz frequency range were made accessible by applying a quantum optical lock-in technique for the first time. This straightforward technique allowed quantum enhancement over a frequency range which reached as low as the range reported for squeezed light sources developed for gravity wave interferometers [4].

E. Conte

Hiroshi Okamoto

We investigate the fundamental limit of biological quantum electron microscopy, which is designed to go beyond the shot noise limit. Inelastic scattering is expected to be the main obstacle in this setting, especially for thick specimens of actual biological interest. Here we describe a measurement procedure that, in principle, significantly neutralizes the effect of inelastic scattering.

ConteE.

Warwick P. Bowen

State-of-the-art microscopes use intense lasers that can severely disturb biological processes, function and viability. This introduces hard limits on performance that only quantum photon correlations can overcome. In this talk I will report recent work from my laboratory which demonstrates this absolute quantum advantage [1]. We show, specifically, that quantum correlations enable signal-to-noise beyond the photodamage-free capacity of conventional microscopy. Broadly, this represents the first demonstration that quantum correlations can allow sensing beyond the limits introduced by optical intrusion upon the measurement process. We achieve this in a coherent Raman microscope, which we use to image molecular bonds within a cell with both quantum-enhanced contrast and sub-wavelength resolution. This allows the observation of nanoscale biological structures that would otherwise not be resolved. Coherent Raman microscopes allow highly selective biomolecular finger-printing in unlabelled specimens, but photodamage is a major roadblock for many applications. By showing that this roadblock can be overcome, our work provides a path towards order-of-magnitude improvements in both sensitivity and imaging speed.