Research Articles:
Programming a D-wave annealing-based quantum computer: tools and
techniques (pp0721-0759)
Scott
Pakin and Steven P. Reinhardt
Quantum annealing is a form of
quantum computing that exploits quantum effects to probabilistically solve a specific,
NP-hard problem: finding the ground state of a classical, Ising-model
Hamiltonian. Because physical quantum annealers are already available, there exists the pressing question of how to
\emph{program}
such systems. That is, how can one map a computational problem
into the coefficients of an Ising-model
Hamiltonian for solution by quantum-annealing hardware? In this article,
we address that question primarily from a practical standpoint. We
survey extant software tools intended for programming
\dw\
annealing-based quantum processors and examine the
programming model and solution technique promoted by each tool in an
attempt to showcase the variety of contemporary approaches to solving
computationally challenging problems on an existing annealing-based
quantum computer.
Span program for
non-binary functions (pp0760-0792)
Salman
Beigi and Leila Taghavi
Span programs characterize the
quantum query complexity of \emph{binary}
functions $f:\{0,\ldots,\ell\}^n \to
\{0,1\}$ up to a constant factor. In
this paper we generalize the notion of span programs for functions with
\emph{non-binary}
input/output alphabets $f: [\ell]^n
\to [m]$. We show that
\emph{non-binary
span program} characterizes the quantum query complexity of any such
function up to a constant factor. We argue that this non-binary span
program is indeed the generalization of its binary counterpart. We also
generalize the notion of span programs for a special class of relations.
Learning graphs provide another tool for designing quantum query
algorithms for binary functions. In this paper, we also generalize this
tool for non-binary functions, and as an application of our
non-binary span program show that any non-binary learning graph gives an
upper bound on the quantum query complexity.
Impossibility of blind quantum sampling for
classical client (pp0793-0806)
Tomoyuki Morimae,
Harumichi Nishimura,
Yuki Takeuchi,
and Seiichiro Tani
Blind quantum computing enables a
client, who can only generate or measure single-qubit
states, to delegate quantum computing to a remote quantum server in such
a way that the input, output, and program are hidden from the server. It
is an open problem whether a completely classical client can delegate
quantum computing blindly (in the information theoretic sense). In this
paper, we show that if a completely classical client can blindly
delegate sampling of
subuniversal
models, such as the
DQC1
model and the
IQP
model, then the polynomial-time hierarchy collapses to the third level.
Our delegation protocol is the one where the client first sends a
polynomial-length bit string to the server and then the server returns a
single bit to the client. Generalizing the no-go result to more general
setups is an open problem.