Boundary scattering tomography of the Bose Hubbard model on general graphs

Correlated quantum many-body phenomena in lattice models have been identified as a set of physically interesting problems that cannot be solved classically. Analog quantum simulators, in photonics and microwave superconducting circuits, have emerged as near-term platforms to address these problems. An important ingredient in practical quantum simulation experiments is the tomography of the implemented Hamiltonians -- while this can easily be performed if we have individual measurement access to each qubit in the simulator, this could be challenging to implement in many hardware platforms. In this paper, we present a scheme for tomography of quantum simulators which can be described by a Bose-Hubbard Hamiltonian while having measurement access to only some sites on the boundary of the lattice. We present an algorithm that uses the experimentally routine transmission and two-photon correlation functions, measured at the boundary, to extract the Hamiltonian parameters at the standard quantum limit. Furthermore, by building on quantum enhanced spectroscopy protocols that, we show that with the additional ability to switch on and off the on-site repulsion in the simulator, we can sense the Hamiltonian parameters beyond the standard quantum limit

Hamiltonian Implementation using Photonic Coupled Cavity Arrays

Thesis (Ph.D.)--University of Washington, 2023Quantum simulators are devices made up of quantum mechanical components that can be used to study otherwise hard-to-probe quantum systems in a laboratory environment. These work by implementing Hamiltonians that accurately describe complex quantum phenomena and allow full control over the underlying parameters dictating the physics. Using photons as particles to study various physical phenomena forms the basis of some of the most promising paradigms for realizing these quantum simulators. A typical photonic quantum simulator consists of a lattice of programmable non-linear resonators, also called coupled cavity arrays (CCAs), with complete access to the Hamiltonian being simulated. While recently, numerous works on quantum simulation with microwave photons have attracted popular attention, using higher-energy optical photons can provide several additional advantages. In this thesis, we engineer photonic CCAs operating in the optical regime, which can be used for various quantum applications. For photonic CCAs to be used as quantum simulators, they need to be scalable, measurable, and controllable. In this work, we go over approaches satisfying each of these criteria. First, we tackle the scalability requirement by demonstrating photonic CCAs implementing the Su-Schrieffer-Heeger (SSH) model describing a polyacetylene molecule. We discuss the operation regime we need to be in for optical CCAs to be scalable to a large number of sites and use the SSH Hamiltonian as a toy model to depict the photonic design requirements that need to be met to do so. We then discuss the measurability of the realized CCAs by proposing algorithms to perform tomography of the implemented Hamiltonians by measuring only at the sites forming the outermost boundaries of these lattices. Next, we focus on adding controllability to our photonic CCAs and, to that end, develop novel thermo-optical heaters that allow us to have active control over the implemented Hamiltonian parameters. Finally, we conclude the thesis by briefly proposing a paradigm whereby, following the approach outlined in this work and utilizing the recent advancements in integrating novel quantum emitters with photonic cavities, we can realize truly scalable photonic quantum simulators

Boundary measurement tomography of the Bose Hubbard model on general graphs

Correlated quantum many-body phenomena in lattice models have been identified as a set of physically interesting problems that cannot be solved classically. Analog quantum simulators, in photonics and microwave superconducting circuits, have emerged as near-term platforms to address these problems. An important ingredient in practical quantum simulation experiments is the tomography of the implemented Hamiltonians—while this can easily be performed if we have individual measurement access to each qubit in the simulator, this could be challenging to implement in many hardware platforms. In this paper, we present a scheme for tomography of quantum simulators which can be described by a Bose-Hubbard Hamiltonian while having measurement access to only some sites on the boundary of the lattice. We present an algorithm that uses the experimentally routine transmission and two-photon correlation functions, measured at the boundary, to extract the Hamiltonian parameters at the standard quantum limit. Furthermore, by building on quantum enhanced spectroscopy protocols that, we show that with the additional ability to switch on and off the on-site repulsion in the simulator, we can sense the Hamiltonian parameters beyond the standard quantum limit

Not Available

Not AvailableThe genomes of a number of halophilic bacilli, isolated from the salt crystallizers of the Rann of Kutch, Gujarat, India, have been sequenced with a view to understanding the mechanism(s) of osmotolerance (1–4). Thalassobacillus devorans strain MSP14 (16S rRNA, GenBank accession no. JX518269), an obligate but moderately halophilic bacterium, was isolated from a salt crystallizer of the Little Rann of Kutch, India. It grows optimally at a concentration of 7.5% NaCl (range, 5 to 15%) in medium at 37°C and pH 7.5. The present genome of MSP14 was sequenced to understand the mechanism(s) of obligate, but moderate, halophilism. By use of the Roche 454 genome sequencer (GS FLX), the genome of Thalassobacillus devorans strain MSP14 (G C content of 42.97%) was sequenced at Macrogen, Inc., South Korea, through Sequencher Tech Pvt., Ltd., Ahmedabad, India. Both shotgun and 3-kb mate-paired library sequencing were performed. Whereas sequencing of shotgun libraries generated 787,155 reads of 439,717,712 bases (average read length of 558 bp), mate-paired libraries generated 140,683 and 131,751 reads of 62,893,040 and 57,724,648 bases, respectively, with average read lengths of 447 and 438 bp, respectively.Not Availabl