85 research outputs found
Mapping Quantum Circuits to IBM QX Architectures Using the Minimal Number of SWAP and H Operations
The recent progress in the physical realization of quantum computers (the
first publicly available ones--IBM's QX architectures--have been launched in
2017) has motivated research on automatic methods that aid users in running
quantum circuits on them. Here, certain physical constraints given by the
architectures which restrict the allowed interactions of the involved qubits
have to be satisfied. Thus far, this has been addressed by inserting SWAP and H
operations. However, it remains unknown whether existing methods add a minimum
number of SWAP and H operations or, if not, how far they are away from that
minimum--an NP-complete problem. In this work, we address this by formulating
the mapping task as a symbolic optimization problem that is solved using
reasoning engines like Boolean satisfiability solvers. By this, we do not only
provide a method that maps quantum circuits to IBM's QX architectures with a
minimal number of SWAP and H operations, but also show by experimental
evaluation that the number of operations added by IBM's heuristic solution
exceeds the lower bound by more than 100% on average. An implementation of the
proposed methodology is publicly available at
http://iic.jku.at/eda/research/ibm_qx_mapping
Exploiting Quantum Teleportation in Quantum Circuit Mapping
Quantum computers are constantly growing in their number of qubits, but
continue to suffer from restrictions such as the limited pairs of qubits that
may interact with each other. Thus far, this problem is addressed by mapping
and moving qubits to suitable positions for the interaction (known as quantum
circuit mapping). However, this movement requires additional gates to be
incorporated into the circuit, whose number should be kept as small as possible
since each gate increases the likelihood of errors and decoherence.
State-of-the-art mapping methods utilize swapping and bridging to move the
qubits along the static paths of the coupling map---solving this problem
without exploiting all means the quantum domain has to offer. In this paper, we
propose to additionally exploit quantum teleportation as a possible
complementary method. Quantum teleportation conceptually allows to move the
state of a qubit over arbitrary long distances with constant
overhead---providing the potential of determining cheaper mappings. The
potential is demonstrated by a case study on the IBM Q Tokyo architecture which
already shows promising improvements. With the emergence of larger quantum
computing architectures, quantum teleportation will become more effective in
generating cheaper mappings.Comment: To appear in ASP-DAC 202
A Language and Hardware Independent Approach to Quantum-Classical Computing
Heterogeneous high-performance computing (HPC) systems offer novel
architectures which accelerate specific workloads through judicious use of
specialized coprocessors. A promising architectural approach for future
scientific computations is provided by heterogeneous HPC systems integrating
quantum processing units (QPUs). To this end, we present XACC (eXtreme-scale
ACCelerator) --- a programming model and software framework that enables
quantum acceleration within standard or HPC software workflows. XACC follows a
coprocessor machine model that is independent of the underlying quantum
computing hardware, thereby enabling quantum programs to be defined and
executed on a variety of QPUs types through a unified application programming
interface. Moreover, XACC defines a polymorphic low-level intermediate
representation, and an extensible compiler frontend that enables language
independent quantum programming, thus promoting integration and
interoperability across the quantum programming landscape. In this work we
define the software architecture enabling our hardware and language independent
approach, and demonstrate its usefulness across a range of quantum computing
models through illustrative examples involving the compilation and execution of
gate and annealing-based quantum programs
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