2 research outputs found
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
Verifying Results of the IBM Qiskit Quantum Circuit Compilation Flow
Realizing a conceptual quantum algorithm on an actual physical device
necessitates the algorithm's quantum circuit description to undergo certain
transformations in order to adhere to all constraints imposed by the hardware.
In this regard, the individual high-level circuit components are first
synthesized to the supported low-level gate-set of the quantum computer, before
being mapped to the target's architecture---utilizing several optimizations in
order to improve the compilation result. Specialized tools for this complex
task exist, e.g., IBM's Qiskit, Google's Cirq, Microsoft's QDK, or Rigetti's
Forest. However, to date, the circuits resulting from these tools are hardly
verified, which is mainly due to the immense complexity of checking if two
quantum circuits indeed realize the same functionality. In this paper, we
propose an efficient scheme for quantum circuit equivalence
checking---specialized for verifying results of the IBM Qiskit quantum circuit
compilation flow. To this end, we combine characteristics unique to quantum
computing, e.g., its inherent reversibility, and certain knowledge about the
compilation flow into a dedicated equivalence checking strategy. Experimental
evaluations confirm that the proposed scheme allows to verify even large
circuit instances with tens of thousands of operations within seconds or even
less, whereas state-of-the-art techniques frequently time-out or require
substantially more runtime. A corresponding open source implementation of the
proposed method is publicly available at https://github.com/iic-jku/qcec.Comment: 10 pages, to be published at International Conference on Quantum
Computing and Engineering (QCE20