Quantum 3.0: Quantum Learning, Quantum Heuristics and Beyond

Quantum learning paradigms address the question of how best to harness conceptual elements of quantum mechanics and information processing to improve operability and functionality of a computing system for specific tasks through experience. It is one of the fastest evolving framework, which lies at the intersection of physics, statistics and information processing, and is the next frontier for data sciences, machine learning and artificial intelligence. Progress in quantum learning paradigms is driven by multiple factors: need for more efficient data storage and computational speed, development of novel algorithms as well as structural resonances between specific physical systems and learning architectures. Given the demand for better computation methods for data-intensive processes in areas such as advanced scientific analysis and commerce as well as for facilitating more data-driven decision-making in education, energy, marketing, pharmaceuticals and health-care, finance and industry

The Art of Science Diplomacy

Richard Holbrooke once said ‘Diplomacy is like jazz: endless variations on a theme’. A fine-art as it seemingly is, diplomacy has recently had an added embellishment on its canvas: science. For the diplomats of the day, this new addition to the vanguard of diplomacy has come with a lot of additional resources and opportunities, over and above the traditional elements of ‘soft power’, which is an approach to international relations that involves persuasion using economic and/ or cultural influences

Quantum Information Processing using the Power-of-SWAP

This project is a comprehensive investigation into the application of the exchange interaction, particularly with the realization of the SWAP^1/n quantum operator, in quantum information processing. We study the generation, characterization and application of entanglement in such systems. Given the non-commutativity of neighbouring SWAP^1/n gates, the mathematical study of combinations of these gates is an interesting avenue of research that we have explored, though due to the exponential scaling of the complexity of the problem with the number of qubits in the system, numerical techniques, though good for few-qubit systems, are found to be inefficient for this research problem when we look at systems with higher number of qubits. Since the group of SWAP^1/n operators is found to be isomorphic to the symmetric group Sn, we employ group-theoretic methods to find the relevant invariant subspaces and associated vector-states. Some interesting patterns of states are found including onedimensional invariant subspaces spanned by W-states and the Hamming-weight preserving symmetry of the vectors spanning the various invariant subspaces. We also devise new ways of characterizing entanglement and approach the separability problem by looking at permutation symmetries of subsystems of quantum states. This idea is found to form a bridge with the entanglement characterization tool of Peres-Horodecki’s Partial Positive Transpose (PPT), for mixed quantum states. We also look at quantum information taskoriented ‘distance’ measures of entanglement, besides devising a new entanglement witness in the ‘engle’. In terms of applications, we define five different formalisms for quantum computing: the circuit-based model, the encoded qubit model, the cluster-state model, functional quantum computation and the qudit-based model. Later in the thesis, we explore the idea of quantum computing based on decoherence-free subspaces. We also investigate ways of applying the SWAP^1/n in entanglement swapping for quantum repeaters, quantum communication protocols and quantum memory.Trinity Barlow Scholarship by Trinity College (University of Cambridge), Nehru Bursary by Nehru Trust for Cambridge University, Hitachi CASE Grant by Hitachi-Cavendish Laboratory, Grants from Semiconductor Physics (SP) and Thin Film Magnetism (TFM) Groups, Cavendish Laboratory, University of Cambridg

Can We Entangle Entanglement?

In this chapter, nested multilevel entanglement is formulated and discussed in terms of Matryoshka states. The generation of such states that contain nested patterns of entanglement, based on an anisotropic XY model has been proposed. Two classes of multilevel-entanglement- the Matryoshka Q-GHZ states and Matryoshka generalised GHZ states, are studied. Potential applications of such resource states, such as for quantum teleportation of arbitrary one, two and three qubits states, bidirectional teleportation of arbitrary two qubit states and probabilistic circular controlled teleportation are proposed and discussed, in terms of a Matryoshka state over seven qubits. We also discuss fractal network protocols, surface codes and graph states as well as generation of arbitrary entangled states at remote locations in this chapter

Diversity from a Fundamental Unity ⵙ and its Projections

In this letter, the underlying basis of nature in physical processes is presented to be that of existence, experience and entirety, encapsulated in ⵙ, a fundamental unity from which space-time, causality and all diversified physical phenomena are posited to emerge. The operative element in the emergence is an apparent flux-entity ξ, through which is projected. We see a trade-off between the inherent entangling and equilibriating tendency of and the dissipative nature of ξ, which leads to self-selection in physical systems

Harnessing Brillouin Interaction in Rare-earth Aluminosilicate Glass Microwires for Optoelectromechanic Quantum Transduction

Quantum transduction, the process of converting quantum signals from one form of energy to another is a key step in harnessing different physical platforms and the associated qubits for quantum information processing. Optoelectromechanics has been one of the effective approaches to undertake transduction from optical-to-microwave signals, among others such as those using atomic ensembles, collective magnetostatic spin excitations, piezoelectricity and electro-optomechanical resonator using Silicon nitride membrane. One of the key areas of loss of photon conversion rate in optoelectromechanical method using Silicon nitride nanomembranes has been those in the electro-optic conversion. To address this, we propose the use of Brillouin interactions in a fiber mode that is allowed to be passed through a fiber taper in rare-earth Aluminium glass microwires. It suggests that we can efficiently convert a $195.57$ THz optical signal to a $325.08$ MHz microwave signal with the help of Brillouin interactions, with a whispering stimulated Brillouin scattering mode yielding a conversion efficiency of $\sim45$\%

Polarization-path-frequency entanglement using interferometry and frequency shifters

Higher dimensional Hilbert space along with ability to control multiple degrees of freedom of photon and entangle them has enabled new quantum protocols for various quantum information processing applications. Here, we propose a scheme to generate and control polarization-path frequency entanglement using the operative elements required to implement a polarization-controlled quantum walk in the path(position) space and frequency domain. Hyperentangled states manifests in the controlled dynamics using an interferometric setup where half-wave plates, beam-splitters and frequency shifters such as those based on the electro-optic effect are used to manipulate the polarization, path and frequency degrees of freedom respectively. The emphasis is on utilizing the polarization to influence the movement to a specific value in the frequency and position space. Negativity between the subspaces is calculated to demonstrate the controllability of the entanglement between them. Progress reported with experimental demonstration of realization of quantum walk using quantum states of light makes quantum walks a practical approach to generate hyperentangled states