Estudo experimental de recursos quânticos usando os computadores quânticos da IBM

• Ano de defesa: 2021
• Autor(a) principal: Pozzobom, Mauro Buemo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; Física; UFSM; Programa de Pós-Graduação em Física; Centro de Ciências Naturais e Exatas
• Palavras-chave em Português: Estados Bell-diagonal; Estados de Werner; Computador quântico; Recursos quânticos; Relações de complementaridade; Bell-diagonal states; Werner states; Quantum computer; Quantum resources; Complementarity relations; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: http://repositorio.ufsm.br/handle/1/21294

Bell-diagonal states are extremely important for understanding the dynamics and applications of some quantum resources. Quantum properties such as steering, entanglement, and coherence, among others, can be used as resources in quantum computing. Because of this, we believe it is necessary to understand the preparation of these states. We create an adjustable quantum circuit, which we implement on the International Business Machines (IBM) quantum computer. These computers are an excellent possibility for carrying out experiments like this. We implement the circuit on three different quantum chips that are available on the online platform. As an example, we measure non-locality, steering, entanglement, discord and non-local coherence for Werner states, which are a special type of the Bell-diagonal. We compare the theoretical results with the experimental data. We note the harmful effect that noise can have on quantum circuits, bringing undesirable decoherence effects to the system. We model noise in a simple way, using two quantum channels, amplitude damping and phase damping. We investigate the direct relationship between measures of discord and entanglement, as well as the sudden change of discord. But, even carrying out these tests on several quantum chips, it was not possible to carry out such verification with great clarity. On the other hand, the great importance of Bohr’s Complementarity Principle for Quantum Mechanics is well known. However, the search for quantifiers to measure wave or particle characteristics, in a quantum system, has always been very intense. Recently, a formalism was developed based on basic properties of the density matrix ( 0; Tr = 1). We use the IBM quantum computer to check the complementarity relationships based on these properties. We calculate quantum coherence, predictability and quantum correlations for a particular class of quantum states of one qubit and also for random quantum states of one, two and three qubits. We note that for both cases, the interaction of the system with the environment, and the consequent creation of correlation, generates a decrease in the sum of quantum coherence and predictability but which is compensated by the increase in quantum correlations between system and environment.