12 research outputs found
A Linear/Producer/Consumer Model of Classical Linear Logic
This paper defines a new proof- and category-theoretic framework for
classical linear logic that separates reasoning into one linear regime and two
persistent regimes corresponding to ! and ?. The resulting
linear/producer/consumer (LPC) logic puts the three classes of propositions on
the same semantic footing, following Benton's linear/non-linear formulation of
intuitionistic linear logic. Semantically, LPC corresponds to a system of three
categories connected by adjunctions reflecting the linear/producer/consumer
structure. The paper's metatheoretic results include admissibility theorems for
the cut and duality rules, and a translation of the LPC logic into category
theory. The work also presents several concrete instances of the LPC model.Comment: In Proceedings LINEARITY 2014, arXiv:1502.0441
Linear/non-Linear Types For Embedded Domain-Specific Languages
Domain-specific languages are often embedded inside of general-purpose host languages so that the embedded language can take advantage of host-language data structures, libraries, and tools. However, when the domain-specific language uses linear types, existing techniques for embedded languages fall short. Linear type systems, which have applications in a wide variety of programming domains including mutable state, I/O, concurrency, and quantum computing, can manipulate embedded non-linear data via the linear type !Ï. However, prior work has not been able to produce linear embedded languages that have full and easy access to host-language data, libraries, and tools.
This dissertation proposes a new perspective on linear, embedded, domain-specific languages derived from the linear/non-linear (LNL) interpretation of linear logic. The LNL model consists of two distinct fragments---one with linear types and another with non-linear types---and provides a simple categorical interface between the two. This dissertation identifies the linear fragment with the linear embedded language and the non-linear fragment with the general-purpose host language.
The effectiveness of this framework is illustrated via a number of examples, implemented in a variety of host languages. In Haskell, linear domain-specific languages using mutable state and concurrency can take advantage of the monad that arises from the LNL model. In Coq, the QWIRE quantum circuit language uses linearity to enforce the no-cloning axiom of quantum mechanics. In homotopy type theory, quantum transformations can be encoded as higher inductive types to simplify the presentation of a quantum equational theory. These examples serve as case studies that prove linear/non-linear type theory is a natural and expressive interface in which to embed linear domain-specific languages
Optimization at the Interface of Unitary and Non-unitary Quantum Operations in PCOAST
The Pauli-based Circuit Optimization, Analysis and Synthesis Toolchain
(PCOAST) was recently introduced as a framework for optimizing quantum
circuits. It converts a quantum circuit to a Pauli-based graph representation
and provides a set of optimization subroutines to manipulate that internal
representation as well as methods for re-synthesizing back to a quantum
circuit. In this paper, we focus on the set of subroutines which look to
optimize the PCOAST graph in cases involving unitary and non-unitary operations
as represented by nodes in the graph. This includes reduction of node cost and
node number in the presence of preparation nodes, reduction of cost for
Clifford operations in the presence of preparations, and measurement cost
reduction using Clifford operations and the classical remapping of measurement
outcomes. These routines can also be combined to amplify their effectiveness.
We evaluate the PCOAST optimization subroutines using the Intel Quantum SDK
on examples of the Variational Quantum Eigensolver (VQE) algorithm. This
includes synthesizing a circuit for the simultaneous measurement of a mutually
commuting set of Pauli operators. We find for such measurement circuits the
overall average ratio of the maximum theoretical number of two-qubit gates to
the actual number of two-qubit gates used by our method to be 7.91.Comment: 10 pages, 8 figures, 3 table
From Symmetric Pattern-Matching to Quantum Control
International audienceOne perspective on quantum algorithms is that they are classical algorithms having access to a special kind of memory with exotic properties. This perspective suggests that, even in the case of quantum algorithms, the control flow notions of sequencing, conditionals, loops, and recursion are entirely classical. There is however, another notion of control flow, that is itself quantum. The notion of quantum conditional expression is reasonably well-understood: the execution of the two expressions becomes itself a superposition of executions. The quantum counterpart of loops and recursion is however not believed to be meaningful in its most general form. In this paper, we argue that, under the right circumstances, a reasonable notion of quantum loops and recursion is possible. To this aim, we first propose a classical, typed, reversible language with lists and fixpoints. We then extend this language to the closed quantum domain (without measurements) by allowing linear combinations of terms and restricting fixpoints to structurally recursive fixpoints whose termination proofs match the proofs of convergence of sequences in infinite-dimensional Hilbert spaces. We additionally give an operational semantics for the quantum language in the spirit of algebraic lambda-calculi and illustrate its expressiveness by modeling several common unitary operations