Research Activities
Room Temperature Quantum Technologies
Quantum theory is one of the most compelling theories to describe nature at atomic scales. One of the most challenging questions associated with quantum mechanics is why we do not observe effects such as quantum superpositions or entanglement in ambient environments at large scales. Extensions of quantum mechanics have been developed to describe the mechanisms which can destroy the “quantumness” of large objects. However exploring this regime of physics requires extraordinary isolation of these large quantum objects from surrounding ambient environments. What emerges when laws of atoms start to dominate over the physics of large objects? Does quantum theory need to be altered to include a transition to classical laws or is there a breakdown at macroscopic scales? In this research we aim to answer these question by nano-designing glassy suspended films on a microchip which can manipulate photons (light) & phonons (sound) simultaneously. These platforms form a promising technology towards the prospects of quantum networks & sensors operating at room temperature.
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Our lab has been developing new techniques to produce nearly any design imaginable in high-stress, nano-thickness membranes for opto-mechanics. So far designs have relied on human instinct or genetic algorithms. In collaboration with Miguel Bessa, we are utilizing the latest in machine learning algorithms in combination with new nanofabrication techniques to design and test new optomechanical systems which go far beyond simple intuition.
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One of our aims is to redesign our micro-mirror sensors to make a new type of optical microphone. These microphones are based on measuring ambient sound by measuring vibrations on tensile membranes with optical cavity readout. One of our challenges is to design these microphones to overcome conventional trade-off between bandwidth and sensitivity. These optomechanical systems should allow for microphones that are resilient to noisy thermal and electromagnetic environments, have low power consumption, and measure with sensitivities only limited by laser quantum shot-noise.
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In this line of work, we aim to create economic, easily implemented navigation systems based on optomechanical sensing with nanophotonic cavities. This aims to design technologies which have recently been used to demonstrate quantum systems at room temperature towards plug-and-play fiber optic systems that can be utilized for high-precision inertial navigation.
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We are working towards cooling nanomechanical oscillators down to their motional ground state from room temperature. The aim is towards on-chip optomechanical technologies which can access quantum behavior in ambient environment with easy-to-use technologies. Our microchip resonators can now achieve vibration isolation from surrounding environments that is now only accessible with optically levitated nanoparticles in high-vacuum. These nano-photonic microchips are promising candidates to enable widespread quantum technologies operating at room temperature.
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One of our aims is to design optical systems which can measure temperatures using ultra-sensitive optomechanical systems. Our research seeks to create systems which are portable, calibration-less, and resilient to outside noise -- one of the major challenges in thermometry.
Developing lightsail materials for ultra-fast space exploration
One of the major aims of nanotechnology is to miniaturize sensors, cameras, and general technology in all dimensions (i.e. x, y and z). In our group, one of the focuses is on unique nanotechnologies that require extreme aspect-ratios. Can we develop techniques to fabricate meter by meter sails with nanometers thickness for future space missions? Can we measure the small nuances of gravity with milligram masses suspended from nanoscale tethers? In our lab we develop techniques that allows such experiments to become a reality by looking at the physics of nano-fabrication.
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We are now aiming at fabrication of highly-reflective, low-absorption, photonic crystals at centimeter scales. These membrane mirrors exhibit record reflectivity from films with sub-wavelength thickness. These light-sail technologies have recently gained attention for as a promising route towards future microchip satellites.
Superconducting Casimir Experiments
Several experimental demonstrations of the Casimir force between two closely-spaced bodies have been realized over the past two decades. Extending the theory to incorporate the behavior of the force between two superconducting plates across their superconducting transition has resulted in many competing predictions. It is clear from these theories that the Casimir effect will be a powerful tool for probing the underlying quantum physics of superconductors on a collective scale (at all frequencies). Experts predict that measuring the Casimir effect between superconductors could allow us to convincingly distinguish between competing theories like the Drude and plasma models as appropriate descriptions of electrons in metals; a major debate in the physics community. Yet, some theories speculate that superconducting Casimir experiments could manifest one of the few testable quantum gravity effects available with current technology. It has widely been postulated that quantum gravity effects are usually so infinitesimal that no conceivable future technology could ever physically measure their existence (as many of the required detectors are calculated to themselves collapse into black holes). To date, no one knows exactly what one should expect to see in the Casimir effect as objects transition into their superconducting state. Our experiments will probe a regime where two famous quantum effects coalesce, where theories with big implications for physics exists and where little experimental data is available due to technological hurdles. We aim to circumvent the need for highly-complex precision experiments by reducing the challenge of stabilization and parallelism to novel microchip design.
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In this project, we'll be measuring the Casimir effect between disordered superconductors (NiTiN) by combining scanning electron microscope with high-aspect-ratio membranes. This will give us one of the clearest looks into the interplay between two quantum materials at cryogenic temperatures. We are currently working closely with collaborators in the Otte Lab.
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There are many exciting implication of measuring changes in the Casimir effect due to superconductivity. It's currently postulated superconductivity's effect on the Casimir force may be amplified with high temperature superconductors. We are currently looking into how these forces could be measured and what is expected. While the physics behind high-temperature multi-layered superconductors remains a mystery, some theories postulate that the large superconducting gaps in these exotic materials could themselves be enabled by the Casimir energy.
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We're collaborating with the theorist to calculate connections between the weak equivalence principle and changes in the Casimir effect between superconductors. Establishing these connections could make null observations in Casimir experiments a rich tool for placing high-precision limits on violations of the universality of free-fall at the quantum level.