233 research outputs found
Innovative tools and technologies for orbital angular momentum based Quantum Information protocols
No full textHigh-dimensional quantum states (qudits) represent a pivotal resource in Quantum Information protocols. Indeed, by exploiting such states, it is possible to increase the amount of information exchanged between parties and to enhance the security of cryptographic schemes. Therefore, several platforms and devices have been proposed and implemented to produce and manipulate qudits. Among these, photonic platforms are particularly interesting since photons represent an ideal candidate for storing and transmitting information. Several degrees of freedom are employed for the information encoding, among them, we focused on the two components of light angular momentum, namely the Spin Angular Momentum (SAM) and the Orbital Angular Momentum (OAM). The former is related to the polarization, therefore, being bidimensional is used to codify qubits, while the latter is related to the field spatial structure and is unbounded, so it is suitable to encode high dimension quantum states. In this thesis work, we investigated the generation, engineering, and detection of OAM states, both proposing and demonstrating innovative approaches. Then, after addressing the main problems arising when working with this degree of freedom, we employed it in two quantum information protocols, namely a quantum machine learning method for state reconstruction and a quantum simulation scheme. We started our study from the sources of OAM states, focusing first on the direct generation of high dimensional entangled states through a Spontaneous Parametric Down Conversion (SPDC) process. Here, we certified the emitted OAM states, introducing a holographic method that outperformed the standard projective measurement approaches, both in time and resources needed for the reconstruction. Then, we addressed the problems connected with the probabilistic nature of SPDC sources, by proposing a platform interfacing a nearly deterministic Quantum Dot (QD) with OAM manipulation devices, in which we demonstrate the production of entangled high dimensional states in this degree of freedom. Thereafter, we investigate the manipulation of the photons state in the engineering of arbitrary qudits and the retrieval of the information stored in them. On the one hand, we optimized an experimental OAM-based QW photonic engineering platform through a black-box approach. Indeed, the latter, not needing to be imbued with a description of the setup, automatically accounts for experimental imperfections, resulting in high values for the fidelities of the engineered states. On the other hand, in our setup, we both enhanced the performance of a well-known measurement approach, namely the holographic techniques, through refined modeling of the beam propagation and demonstrated innovative machine learning-based reconstruction techniques, capable of reducing the losses present in interferometric and diffractive schemes. Finally, as we said, we make use of the potential connected with a high dimensional encoding inside two quantum information processing protocols. We first identified the OAM-based QW dynamics as the reservoir of a quantum extreme learning paradigm, introducing an estimation method for qubits properties that is effective and resource-efficient. Then, we exploited the connection between the QW evolution and the one-dimensional Dirac equation, and, by codifying the particle position in the OAM of single photons, we simulated the Zitterbewegung effect, i.e the trembling motion occurs during the free evolution of relativistic particles. Both implementations are prelaminar results, but they showcase promising performance in the application of the approaches to higher dimensional states and in the photonic simulation of more complex dynamics
Sonnino visto da un notabile di provincia: dalle Memorie di Nello Toscanelli
No full textE' un interessante ritratto del giovane Sonnino visto con gli occhi di Nello Toscanelli, che lo incontrò in casa della zia Emilia, nei corridoi del parlamento e in vari circoli romani nella seconda metà dell'800
Interferometric imaging of amplitude and phase of spatial biphoton states
No full textHigh-dimensional biphoton states are promising resources for quantum applications, ranging from high-dimensional quantum communications to quantum imaging. A pivotal task is fully characterising these states, which is generally time-consuming and not scalable when projective measurement approaches are adopted. However, new advances in coincidence imaging technologies allow for overcoming these limitations by parallelising multiple measurements. Here, we introduce biphoton digital holography, in analogy to off-axis digital holography, where coincidence imaging of the superposition of an unknown state with a reference one is used to perform quantum state tomography. We apply this approach to single photons emitted by spontaneous parametric down-conversion in a nonlinear crystal when the pump photons possess various quantum states. The proposed reconstruction technique allows for a more efficient (3 order-of-magnitude faster) and reliable (an average fidelity of 87%) characterisation of states in arbitrary spatial modes bases, compared with previously performed experiments. Multi-photon digital holography may pave the route toward efficient and accurate computational ghost imaging and high-dimensional quantum information processing
Photonic cellular automaton simulation of relativistic quantum fields: Observation of Zitterbewegung
No full textQuantum cellular automaton (QCA) is a model for universal quantum computation and a natural candidate for digital quantum simulation of relativistic quantum fields. Here we introduce the first photonic platform for implementing QCA simulation of a free relativistic Dirac quantum field in 1+1 dimension, through a Dirac quantum cellular automaton (DQCA). Encoding the field position degree of freedom in the orbital angular momentum (OAM) of single photons, our state-of-the-art setup experimentally realizes eight steps of a DQCA, with the possibility of having complete control over the input OAM state preparation and the output measurement making use of two spatial light modulators. Therefore, studying the distribution in the OAM space at each step, we were able to reproduce the time evolution of the free Dirac field observing the Zitterbewegung, an oscillatory movement extremely difficult to see in a real-case experimental scenario that is a signature of the interference of particle and antiparticle states. The accordance between the expected and measured Zitterbewegung oscillations certifies the simulator performances, paving the way towards the application of photonic platforms to the simulation of more complex relativistic effects
Building Stronger Communities Through Sustained Activism
No full textWhen it comes to human rights and social justice activism in the United States, it’s hard to find a cause in which Helen Zia hasn’t been directly involved.
An award-winning journalist and author, Zia is a second-generation Chinese-American and through her decades-long career has worked on issues ranging from Asian-American civil rights to LGBTQ+ issues to labor rights and more.
On April 17th, 2023, Zia shared stories from her lifetime of activism, sustaining social movements for the long term, and challenging the model-minority myth in a presentation titled “Building Stronger Communities Through Sustained Activism.”
The event, held Gonzaga University’s Myrtle Woldson Performing Arts Center at 6 p.m., was free and open to the public, and was sponsored by GU’s Asian American Union, Filipino American Student Union, the Critical Race and Ethnic Studies department, and the Office of the President. This is the second time Zia has shared her thoughts and perspectives with the Gonzaga community as she presented via a Zoom event in 2021.
Born in Newark, New Jersey, Zia was part of Princeton University’s first coeducational graduating class. She started medical school, but quit soon thereafter to move to Detroit to work as an autoworker, construction laborer and community organizer. She found a passion for journalism roughly at the same time a local Chinese American man, Vincent Chin, was killed in a racially-motivated assault. Her coverage drew attention to the ways that Asian Americans are targeted.
Zia went on to become executive editor of Ms. magazine and a regular contributor to outlets ranging from The New York Times to The Nation to The Advocate. Her first book, “Asian American Dreams: The Emergence of an American People,” was published in 2000, and her most recent book, 2019’s “Last Boat Out of Shanghai: The Epic Story of Those Who Fled Mao’s Revolution,” was named one of NPR’s best books of the year
Apparent bias: the inclusion of police officers on the jury and Article 6.1 of the Human Rights Act
No full textIn this article Zia Akhtar (Barrister, Grays Inn) looks at the jury trial and the inclusion of members of the police force that may lead to a breach of Article 6 of the Human Rights Act 1998. The author explains tests for determination of bias, the role of judicial discretion and the consideration of conflicts of interest
Dr. Zia Ul Hassan: Poetic and Literary Dimensions
No full textDr. Zia-ul-Hasan (b. 1964) first gained recognition as a poet. Before the 1990s, during the twentieth century, the literary circle Halqa-e-Arbab-e-Zouq had already acknowledged the maturity of his poetry. His poetic collections, including Bar-e-Musalsal (1996), Adhi Bhook aur Puri Galiyan (2007), and Azal Se (2014), have earned widespread acclaim. His poetry embodies the elements of asceticism, mysticism, and a wandering spirit. During his M.A., he wrote a critical thesis on the poetry of N.M. Rashed, which later formed the basis of the Pakistani Adab ke Mimar series on Rashed's life and work. His doctoral dissertation, titled Urdu Tanqeed ka Umrani Dabistan (The Sociological School of Urdu Criticism), was published by the West Pakistan Academy, Lahore. Dr. Zia-ul-Hasan served as a professor of Urdu literature at Oriental College, Punjab University. His teaching philosophy aimed to connect students directly with original texts and encourage them to form independent opinions before consulting critics, fostering a deep and enduring relationship with literary study. This essay is a humble attempt by the author, who had the privilege of learning from Dr. Zia-ul-Hasan as both a student and a colleague, to capture a glimpse of his poetic themes and metaphors. It reflects a sincere effort to explore the depth of Dr. Zia-ul-Hasan’s literary contributions
The changing patterns of Bangladesh foreign policy: a comparative study of the Mujib and Zia regimes (1971-1981), 1995
No full textThis study has highlighted the changes in Bangladesh foreign policy during the Mu jib and Zia regimes. It has uncovered the fact that the foreign policy of the Sheikh Mu jib regime was shaped by the principles of the national liberation war of Bangladesh (secularism and socialism) although the post-liberation reality demanded the supremacy of the national interest in the foreign policy formulation of the new nation. Because of Mujib's central priority on the principles of the national liberation war, his foreign policy was tilted towards India and the Soviet Union, as the two key international actors of Bangladesh's national liberation war. Due to their skeptical role in the liberation war the United States, China, and the Muslim world were kept away from the preferential treatment. As the Indo-Soviet allies failed to meet the emerging needs and growing economic crisis, Mujib's foreign policy failed to achieve the national interest and it proved dysfunctional. On the other hand, following the eclipse of the Mu jib regime and at the beginning of the Zia era, a thaw began in the foreign policy decision-making process of Bangladesh. Ziaur Rahman considered the national interest as a vantage point and put top priority on it (self preservation, economic advancement, safe-guarding as well as augmenting national power and upholding national ideology). In order to achieve the national interest Zia very promptly transformed Bangladesh's foreign policy from the Indo-Soviet orbit, got rid of the socialist yoke, and aligned with the United States, China, and the Muslim world triangle . Zia1s redesigned foreign policy has successfully explored sufficient external resources to meet the mounting economic crisis and to a great extent contributed to the economic development of Bangladesh. Although the Indo-Soviet threat was posed to the state under Zia, the new alliance of the United States, China, and the Muslim world effectively forestalled the threat and the national interest was served better than during the Mujib regime
introducing and checking style of zia al Zia al-Kūlub Fī Akhlaq al-Matlub a new discovered prose effect of imitate Sa'di's Golestan
No full textThere are many texts on ethical issues that each has been trying to save human values and ethical virtues . Among these works, the valuable book of Zia al-Kūlub Fī Akhlaq al-Matlub is written by Seyyed Mohammad Zia al-Din Hosseini Mazandarani Esfahani known as Hosseini Marashi , which in the eleventh century was drafted into prose and ordered to imitate Sa'di's Golestan . Zia al-Kalwb Fī Akhlaq al-Mutlaub is a detailed book on moral issues based on Qur'anic verses, verses, stories and poems written by Shah Abbas I Safavi , written in one title and two phrases, each in several phrases .The author has not been named in any texts.The research suggests that for the first time, this research attemted to introduce the present effect with the depth of its effect to recognize , its linguistic, intellectual and literary values, relying on the underlying cognitive style to make this valuable work more visible . Since this book has not yet been corrected or ornamented, the study of its style from the complementary rings is a kind of Persian prose style in the Safavid era
The effect of demographic changes on saving for life cycle motives in developing countries
No full textIf developing countries follow the same paths that industrialized countries have followed, saving for retirement will initially become more important as the population growth rate declines. To calculate the potential importance of life-cycle savings (saving for retirement), the paper presents a simulation model that translates demographic projections into savings-rate projections. It simulated aggregate rates for life-cycle savings for Brazil, China, Korea, Mexico, Nigeria, Pakistan and Turkey. The savings rates increase 5 or 6 percentage points when the last baby boomers enter the work force and begin to save after their children leave home. The effect on life-cycle savings is dramatic; the effect on total savings rates which are often three or four times as high, is not. Simulated life-cycle savings rates peak at an absolute 10 percent or less in all cases. The patterns of these projections seem robust with regard to assumptions about productivity growth, interest rates, and age-specific participation in the labor force.Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research,Health Monitoring&Evaluation,Inequality
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