Quantum Zeno Effect in the Decoherent Histories

The quantum Zeno effect arises due to frequent observation. That implies the existence of some experimenter and its interaction with the system. In this contribution, we examine what happens for a closed system if one considers a quantum Zeno type of question, namely: "what is the probability of a system, remaining always in a particular subspace". This has implications to the arrival time problem that is also discussed. We employ the decoherent histories approach to quantum theory, as this is the better developed formulation of closed system quantum mechanics, and in particular, dealing with questions that involve time in a non-trivial way. We get a very restrictive decoherence condition, that implies that even if we do introduce an environment, there will be very few cases that we can assign probabilities to these histories, but in those cases, the quantum Zeno effect is still present.Comment: 7 pages, To appear in DICE 2006 (Decoherence Information Complexity and Entropy) conference proceeding

Quantum Zeno Effect in the Decoherent Histories

The quantum Zeno effect arises due to frequent observation. That implies the existence of some experimenter and its interaction with the system. In this contribution, we examine what happens for a closed system if one considers a quantum Zeno type of question, namely: "what is the probability of a system, remaining always in a particular subspace". This has implications to the arrival time problem that is also discussed. We employ the decoherent histories approach to quantum theory, as this is the better developed formulation of closed system quantum mechanics, and in particular, dealing with questions that involve time in a non-trivial way. We get a very restrictive decoherence condition, that implies that even if we do introduce an environment, there will be very few cases that we can assign probabilities to these histories, but in those cases, the quantum Zeno effect is still present.Comment: 7 pages, To appear in DICE 2006 (Decoherence Information Complexity and Entropy) conference proceeding

Views on the TRIPS Agreement to find an approach to increase the access to pharmaceutical products in developing countries : a need for transforming the global medicine regime?

Lack of access to pharmaceutical products in developing countries is major problem due to strict patent protection. The aim of the thesis is to find out whether one of the suggested approaches could increase the access to pharmaceutical products by analyzing the TRIPS Agreement and discussing few ways to view it. The views are from the perspectives of public health, right to health as well as generic medicines. The analyzed approaches are the Medicine Patent Pool, Open-Source model and Orphan medicines. An analysis of whether the global medicine regime needs transforming will be discussed before concluding the thesis that in order to increase access to pharmaceuticals in developing countries, it is essential to choose the right view on the TRIPS Agreement and then chose the right approach for practical application that supports the chosen vision. The theoretical analysis and discussion are conducted by examining the TRIPS Agreement and Doha Declaration as well as by critically analyzing and commenting on the books and articles written by legal scholars on the similar topics.Kehitysmaiden pääsy farmaseuttisiin tuotteisiin johtuu tiukoista patenttisuojauksista. Analysoimalla TRIPS sopimusta ja keskustelemalla sen eri tulkintatavoista, tämän tutkielman tavoite on selvittää, josko yksi ehdotetuista lähestymistavoista voisi lisätä farmaseuttisten tuotteiden saatavuutta. Tulkintatapoja ovat kansanterveyden, oikeus terveyteen sekä geneeristen lääkkeiden perspektiivit. Lähestymistavat, joita analysoidaan ovat lääkkeiden patenttipooli, avoimen lähdekoodin malli ja orpolääkkeet. Analysoinnista, josko maailmanlaajuinen lääkejärjestelmä tulisi muuttaa, keskustellaan, ennen kuin tutkielma lopettaa toteumaan, että jotta farmaseuttisten tuotteiden saatavuutta kehitysmaissa voidaan parantaa, on tärkeää valita oikea tulkintatapa TRIPS sopimuksesta ja sitten valita oikea lähestymistapa käytännön toteutukseen, joka tukee valittua näkemystä. Teoreettinen analysointi ja keskustelu on toteutettu tutkimalla TRIPS sopimusta, Dohan julistusta sekä kriittisesti analysoimalla ja kommentoimalla kirjoja ja artikkeleja samanlaisista aiheista, jotka ovat kirjoittaneet oikeustieteilijät

IMPLEMENTING GENRE PEDAGOGY IN CONTENT INSTRUCTION: LESSONS FROM SWEDEN

Drawing upon studies conducted in Sweden, this article discusses possibilities and limits of implementing genre pedagogy in content instruction. The wider educational concern is how knowledge of genre and language can be used to promote a deeper engagement with content knowledge. The linguistic theory underpinning genre pedagogy and the pedagogic-practical teaching/learning cycle is explained. Then, two empirical studies of genre-based teaching in Geography in Grade 6 are reviewed, with a particular focus on the texts used as models for the students own writing. The studies show two contrasting sides of genre-based intervention: one in which generic structures and other features of texts are used productively to engage with content knowledge and one in which attention to generic structure and logical connections comes at the expense of the negotiation of content knowledge. The article concludes with recommendations for implementing genre pedagogy.DOI: 10.24071/ijiet.2020.04010

Evolving objective function for improved variational quantum optimization

A promising approach to useful computational quantum advantage is to use variational quantum algorithms for optimisation problems. Crucial for the performance of these algorithms is to ensure that the algorithm converges with high probability to a near-optimal solution in a small time. In Barkoutsos et al (Quantum 2020) an alternative class of objective functions, called Conditional Value-at-Risk (CVaR), was introduced and it was shown that they perform better than standard objective functions. Here we extend that work by introducing an evolving objective function, which we call Ascending-CVaR and that can be used for any optimisation problem. We test our proposed objective function, in an emulation environment, using as case-studies three different optimisation problems: Max-Cut, Number Partitioning and Portfolio Optimisation. We examine multiple instances of different sizes and analyse the performance using the Variational Quantum Eigensolver (VQE) with hardware-efficient ansatz and the Quantum Approximate Optimization Algorithm (QAOA). We show that Ascending-CVaR in all cases performs better than standard objective functions or the "constant" CVaR of Barkoutsos et al (Quantum 2020) and that it can be used as a heuristic for avoiding sub-optimal minima. Our proposal achieves higher overlap with the ideal state in all problems, whether we consider easy or hard instances -- on average it gives up to ten times greater overlap at Portfolio Optimisation and Number Partitioning, while it gives an 80% improvement at Max-Cut. In the hard instances we consider, for the number partitioning problem, standard objective functions fail to find the correct solution in almost all cases, CVaR finds the correct solution at 60% of the cases, while Ascending-CVaR finds the correct solution in 95% of the cases.Comment: 20 pages, 13 figures; v3 published versio

Practical parallel self-testing of Bell states via magic rectangles

Self-testing is a method to verify that one has a particular quantum state from purely classical statistics. For practical applications, such as device-independent delegated verifiable quantum computation, it is crucial that one self-tests multiple Bell states in parallel while keeping the quantum capabilities required of one side to a minimum. In this work, we use the $3 \times n$ magic rectangle games (generalizations of the magic square game) to obtain a self-test for $n$ Bell states where the one side needs only to measure single-qubit Pauli observables. The protocol requires small input sizes (constant for Alice and $O(\log n)$ bits for Bob) and is robust with robustness $O(n^{5/2} \sqrt{\varepsilon})$, where $\varepsilon$ is the closeness of the ideal (perfect) correlations to those observed. To achieve the desired self-test we introduce a one-side-local quantum strategy for the magic square game that wins with certainty, generalize this strategy to the family of $3 \times n$ magic rectangle games, and supplement these nonlocal games with extra check rounds (of single and pairs of observables).Comment: 29 pages, 6 figures; v3 minor corrections and changes in response to comment

Quantum Zeno effect in the decoherent histories

The quantum Zeno effect arises due to frequent observation. That implies the existence of some experimenter and its interaction with the system. In this contribution, we examine what happens for a closed system if one considers a quantum Zeno type of question, namely: "what is the probability of a system, remaining always in a particular subspace". This has implications to the arrival time problem that is also discussed. We employ the decoherent histories approach to quantum theory, as this is the better developed formulation of closed system quantum mechanics, and in particular, dealing with questions that involve time in a non-trivial way. We get a very restrictive decoherence condition, that implies that even if we do introduce an environment, there will be very few cases that we can assign probabilities to these histories, but in those cases, the quantum Zeno effect is still present.Comment: 7 pages, To appear in DICE 2006 (Decoherence Information Complexity and Entropy) conference proceeding