Programming Telepathy: Implementing Quantum Non-Locality Games

Quantum pseudo-telepathy is an intriguing phenomenon which results from the application of quantum information theory to communication complexity. To demonstrate this phenomenon researchers in the field of quantum communication complexity devised a number of quantum non-locality games. The setting of these games is as follows: the players are separated so that no communication between them is possible and are given a certain computational task. When the players have access to a quantum resource called entanglement, they can accomplish the task: something that is impossible in a classical setting. To an observer who is unfamiliar with the laws of quantum mechanics it seems that the players employ some sort of telepathy; that is, they somehow exchange information without sharing a communication channel. This paper provides a formal framework for specifying, implementing, and analysing quantum non-locality games

Programming with Quantum Communication

This work develops a formal framework for specifying, implementing, and analysing quantum communication protocols. We provide tools for developing simple proofs and analysing programs which involve communication, both via quantum channels and exhibiting the LOCC (local operations, classical communication) paradigm

Optimal planning with temporal logic specifications

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (p. 117-121).Most of the current uninhabitated Aerial Vehicles (UAVs) are individually monitored, commanded and controlled by several operators of different expertise. However, looking forward, there has been a recent interest in multiple-UAV systems, in which the system is only provided with the high-level goals and constraints, called the "mission specifications," and asked to navigate the UAVs such that the mission specifications are fulfilled. A crucial part in designing such multiple-UAV systems is the development of coordination and planning algorithms that, given a set of high-level mission specifications as input, can synthesize provably correct and possibly optimal schedules for each of the UAVs. This thesis studies optimal planning problems in a multiple-UAV mission planning setting, where the mission specifications are given in formal languages. The problem is posed as a novel variant of the Vehicle Routing Problem (VRP), in which temporal logics and process algebra are utilized to represent a large class of mission specifications in a systematic way. The thesis is structured in two parts. In the first part, two temporal logics that are remarkably close to the natural language, namely the linear temporal logic LTL-x and the metric temporal logic (MTL), are considered for specification of a large class of temporal and logical constraints in VRPs. Mixed-integer linear programming based algorithms, which solve these variants of the VRP to optimality, are presented. In the second part, process algebra is introduced and used as a candidate for the same purpose.(cont.) A tree search based anytime algorithm is given; this algorithm is guarranteed to find a best-first feasible solution in polynomial time and improve it to an optimal one in finite time.by Sertac Karaman.S.M

Lambda calculi and logics for quantum computing

In questa tesi proponiamo diversi risultati originali riguardo i lambda calcoli e le logiche per le computazioni quantistiche. Il lavoro `e diviso in tre parti. Nella prima parte richiamiamo alcune nozioni fondamentali di algebra lineare, logica e computazione quantistica. La seconda parte volge l\u2019attenzione ai lambda calcoli quantistici. Introdurremo dapprima Q, un lambda calcolo quantistico con controllo classico. Studieremo le sue proprie`a classiche, come la confluenza e la Subject Reduction, proseguendo poi con un\u2019importante propriet`a quantistica, chiamata standardizzazione. In seguito sar`a studiato il potere espressivo di Q, attraverso la provata equivalenza con il formalismo delle famiglie di circuiti quantistici. A partire da Q, sar`a poi definito e studiato il sottolinguaggio SQ, ispirato alla Soft Linear Logic ed intrinsecamente polytime. Sia Q sia SQ non hanno nella sintassi un operatore di misurazione, e quindi un\u2019implicita misurazione viene assunta alla fine delle computazioni. I problemi relativi alla misura sono studiati in un terzo lambda calcolo chiamato Q*, che estende Q con un operatore di misura. Partendo dall\u2019osservazione che un esplicito operatore di misura interrompe l\u2019evoluzione altrimenti deterministica del calcolo, importando un comportamento probabilistico, sono stati definiti dei nuovi strumenti tecnici quali le computazioni probabilistiche e gli stati misti. Proveremo un forte teorema di confluenza, valido anche nell\u2019importante caso delle computazioni infinite. Nella terza parte della tesi studieremo invece due sistemi modali etichettati, chiamati rispettivamente MSQS e MSpQS, che permettono di ragionare qualitativamente sulle computazioni quantistiche. I due sistemi rappresentano un possibile punto di partenza verso un nuovo modello per ragionare qualitativamente sulle trasformazioni computazionali degli stati quantistici, viste come modelli di Kripke. 1In this thesis we propose several original results about lambda calculi and logics for quantum computing. The work is divided into three parts. The first one is devoted to recall the main notions about linear algebra, logics and quantum computing. The second and main part focalizes on quantum lambda calculi. We start with Q, a quantum lambda calculus with classical control. We study its classical properties, such as confluence and Subject Reduction. We go on with an important quantum property of Q, called standardization, and successively, we study the expressive power of the proposed calculus, by proving the equivalence with the computational model of quantum circuit families. From the calculus Q, subsequently a sublanguage of Q called SQ is defined and studied: SQ is inspired to the Soft Linear Logic and it is a quantum lambda calculus intrinsically poly-time. Since Q and SQ have not an explicit measurement operator in the syntax, an implicit measurement at the end of the computations is assumed. Measurement problems are explicitly studied in a third quantum lambda calculus called Q*, an extension of Q with a measurement operator. Starting from the observation that an explicit measurement operator breaks the deterministic evolution of the computation by importing a probabilistic behavior, new technical instruments, such as the probabilistic computations and the mixed states are defined. We prove a confluence result for the calculus, also for the relevant case of infinite computations. In the last part of the thesis, we propose two labeled modal deduction systems able to describe quantum computations from a qualitative point of view. The two systems, called respectively MSQS and MSpQS, represent a starting point toward a new model to deal (in a qualitative way) with computational quantum structures, seen as Kripke models.

Formal verification techniques using quantum process calculus

Quantum communication is a rapidly growing area of research and development. While the successful construction of a large-scale quantum computer may be some years away, there are already commercial implementations of secure communication using quantum cryptography. The application of formal methods to classical communication and cryptographic systems has been very successful, and is now widely used in industry by organisations such as Intel, Microsoft and NASA. There is reason to believe that similar benefits can be expected for the verification of quantum systems. In this thesis, we focus on the use of process calculus, specifically Communicating Quantum Processes (CQP), for the analysis of quantum protocols. Congruence relations are an important aspect of process calculus, since they provide the foundation for equational reasoning. Previous work on congruence relations for quantum processes excluded the classical information arising from measurements, and was therefore unable to analyse many of the interesting known quantum communication protocols. Developing a congruence relation for general quantum processes is difficult because of the interaction between measurement, entanglement and parallel composition. We define a labelled transition relation for CQP in order to describe external interactions. Based on this semantics, we define a notion of observational equivalence for CQP processes, namely probabilistic branching bisimilarity. We find that this relation is not preserved by parallel composition, however we are able to gain a deeper understanding of the link between probabilistic branching and measurement. Based on this newfound understanding, we present a novel semantics for quantum processes, combining mixed quantum states with probabilistic branching. With respect to this new semantic model, we define full probabilistic branching bisimilarity and prove that it is a congruence. We use this congruence relation to discuss an axiomatic approach to the verification of quantum processes. The quantum teleportation protocol is used as a primary example throughout, and we prove that it is congruent to a quantum channel. We define a translation from CQP to the Quantum Model Checker (QMC) in order to provide automated verification techniques using CQP specifications. We prove that this translation preserves the semantics of CQP processes, thereby enabling a multifaceted approach to formal verification by enhancing the manual techniques of process calculus with the benefits of model checking

Abstract QPL 2005 A Process Algebra for Reasoning About Quantum Security

We present a process algebra for specifying and reasoning about quantum security protocols. Since the computational power of the protocol agents must be restricted to quantum polynomial-time, we introduce the logarithmic cost quantum random access machine (QRAM) similar to [4,6], and incorporate it in the syntax of the algebra. Probabilistic transition systems give the semantic for the process algebra. Term reduction is stochastic because quantum computation is probabilistic and, moreover, we consider a uniform scheduler to resolve non-deterministic choices. With the purpose of defining security properties, we introduce observational equivalence and quantum computational indistinguishability, and show that the latter is a congruence relation. A simple corollary of this result asserts that any security property defined via emulation is compositional. Finally, we illustrate our approach by establishing the concept of quantum zero-knowledge protocol