11,877 research outputs found
High-fidelity two-qubit gates of hybrid superconducting-semiconducting singlet-triplet qubits
Hybrid systems comprising superconducting and semiconducting materials are
promising architectures for quantum computing. Superconductors induce
long-range interactions between the spin degrees of freedom of semiconducting
quantum dots. These interactions are widely anisotropic when the semiconductor
material has strong spin-orbit interactions. We show that this anisotropy is
tunable and enables fast and high-fidelity two-qubit gates between
singlet-triplet (ST) spin qubits. Our design is immune to leakage of the
quantum information into non-computational states and removes always-on
interactions between the qubits, thus resolving key open challenges for these
architectures. Our ST qubits do not require additional
technologically-demanding components nor fine-tuning of parameters. They
operate at low magnetic fields of a few milli Tesla and are fully compatible
with superconductors. In realistic devices, we estimate infidelities below
, that could pave the way toward large-scale hybrid
superconducting-semiconducting quantum processors
Large-scale quantum hybrid solution for linear systems of equations
State-of-the-art noisy intermediate-scale quantum devices (NISQ), although
imperfect, enable computational tasks that are manifestly beyond the
capabilities of modern classical supercomputers. However, present quantum
computations are restricted to exploring specific simplified protocols, whereas
the implementation of full-scale quantum algorithms aimed at solving concrete
large scale problems arising in data analysis and numerical modelling remains a
challenge. Here we introduce and implement a hybrid quantum algorithm for
solving linear systems of equations with exponential speedup, utilizing quantum
phase estimation, one of the exemplary core protocols for quantum computing. We
introduce theoretically classes of linear systems that are suitable for current
generation quantum machines and solve experimentally a -dimensional
problem on superconducting IBMQ devices, a record for linear system solution on
quantum computers. The considered large-scale algorithm shows superiority over
conventional solutions, demonstrates advantages of quantum data processing via
phase estimation and holds high promise for meeting practically relevant
challenges.Comment: 8 pages, 6 figure
Scalable Ion Trap Quantum Computing without Moving Ions
A hybrid quantum computing scheme is studied where the hybrid qubit is made
of an ion trap qubit serving as the information storage and a solid-state
charge qubit serving as the quantum processor, connected by a superconducting
cavity. In this paper, we extend our previous work [1] and study the
decoherence, coupling and scalability of the hybrid system. We present our
calculations of the decoherence of the coupled ion - charge system due to the
charge fluctuations in the solid-state system and the dissipation of the
superconducting cavity under laser radiation. A gate scheme that exploits rapid
state flips of the charge qubit to reduce decoherence by the charge noise is
designed. We also study a superconducting switch that is inserted between the
cavity and the charge qubit and provides tunable coupling between the qubits.
The scalability of the hybrid scheme is discussed together with several
potential experimental obstacles in realizing this scheme
Atomic-Scale Interface Engineering of Majorana Edge Modes in a 2D Magnet-Superconductor Hybrid System
Topological superconductors are predicted to harbor exotic boundary states -
Majorana zero-energy modes - whose non-Abelian braiding statistics present a
new paradigm for the realization of topological quantum computing. Using
low-temperature scanning tunneling spectroscopy (STS), we here report on the
direct real-space visualization of chiral Majorana edge states in a monolayer
topological superconductor, a prototypical magnet-superconductor hybrid system
comprised of nano-scale Fe islands of monoatomic height on a
Re(0001)-O(21) surface. In particular, we demonstrate that interface
engineering by an atomically thin oxide layer is crucial for driving the hybrid
system into a topologically non-trivial state as confirmed by theoretical
calculations of the topological invariant, the Chern number.Comment: 26 pages, 9 figure
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