Anyonic interferometry without anyons: how a flux qubit can read out a topological qubit

  title={Anyonic interferometry without anyons: how a flux qubit can read out a topological qubit},
  author={Fabian Hassler and A. Akhmerov and Chang-Yu Hou and C. W. J. Beenakker},
  journal={New Journal of Physics},
Proposals to measure non-Abelian anyons in a superconductor by quantum interference of vortices suffer from the predominantly classical dynamics of the normal core of an Abrikosov vortex. We show how to avoid this obstruction using coreless Josephson vortices, for which the quantum dynamics has been demonstrated experimentally. The interferometer is a flux qubit in a Josephson junction circuit, which can non-destructively read out a topological qubit stored in a pair of anyons—even though the… 

Figures from this paper

Minimal circuit for a flux-controlled Majorana qubit in a quantum spin-Hall insulator
We construct a minimal circuit, based on the top-transmon design, to rotate a qubit formed out of four Majorana zero-modes at the edge of a two-dimensional topological insulator. Unlike braiding
Braiding quantum circuit based on the 4π Josephson effect
We propose a topological qubit in which braiding and readout are mediated by the $4\ensuremath{\pi}$ Majorana-Josephson effect. The braidonium device consists of three Majorana nanowires that come
Flux qubit in a dc SQUID with the 4π period Josephson effect
We propose a superconducting flux qubit in a dc SQUID structure, formed by a conventional insulator Josephson junction and a topological nanowire Josephson junction with Majorana bound states. The
Landau-Zener-Stückelberg Interferometry for Majorana Qubit
It is shown that the time evolution of superconducting phase difference at the junction under a voltage bias induces an oscillation in energy levels of the Majorana parity states, whereas the level-crossing is avoided by a small coupling energy of MQs in the individual 1D superconductors.
Strong coupling between a topological qubit and a nanomechanical resonator
We describe a scheme that enables a strong coherent coupling between a topological qubit and the quantized motion of a magnetized nanomechanical resonator. This coupling is achieved by attaching an
Coherent dynamics in long fluxonium qubits
We analyze the coherent dynamics of a fluxonium device (Manucharyan et al 2009 Science 326 113) formed by a superconducting ring of Josephson junctions in which strong quantum phase fluctuations are
All-electrically reading out and initializing topological qubits with quantum dots
We analyze the reading and initialization of a topological qubit encoded by Majorana fermions in one-dimensional semiconducting nanowires, weakly coupled to a single level quantum dot (QD). It is
SWAP gate between a Majorana qubit and a parity-protected superconducting qubit
High fidelity quantum information processing requires a combination of fast gates and long-lived quantum memories. In this work, we propose a hybrid architecture, where a parity-protected
The hybrid topological longitudinal transmon qubit
We introduce a new hybrid qubit consisting of a Majorana qubit interacting with a transmon longitudinally coupled to a resonator. To do so, we equip the longitudinal transmon qubit with topological
Flux-controlled quantum computation with Majorana fermions
uxes. We show that readout operations can also be fully ux-controlled, without requiring microscopic control over tunnel couplings. We identify the minimal circuit that can perform the


Electrically detected interferometry of Majorana fermions in a topological insulator.
This work shows how a pair of neutral Majorana fermions can be converted reversibly into a charged Dirac fermion, and enables electrical detection of a qubit by an interferometric measurement.
Implementing arbitrary phase gates with Ising anyons.
This work proposes a method of implementing arbitrary single-qubit phase gates for Ising anyons by running a current of anyons with interfering paths around computational anyons.
Majorana fermions in a tunable semiconductor device
The experimental realization of Majorana fermions presents an important problem due to their non-Abelian nature and potential exploitation for topological quantum computation. Very recently Sau et
Quantum dynamics of a single vortex
By measuring the statistics of the vortex escape from a controllable pinning potential, this work demonstrates the existence of quantized levels of the Vortex energy within the trapping potential well and quantum tunnelling of theortex through the pinning barrier.
Non-Abelian Anyons and Topological Quantum Computation
Topological quantum computation has emerged as one of the most exciting approaches to constructing a fault-tolerant quantum computer. The proposal relies on the existence of topological states of
Suppression of tunneling in a superconducting persistent-current qubit
We consider a superconducting persistent-current qubit consisting of a three-junction superconducting loop in an applied magnetic field. We show that by choosing the field, Josephson couplings, and
Aharonov-Casher-effect suppression of macroscopic tunneling of magnetic flux.
A system in which the amplitude of macroscopic flux tunneling can be modulated via the Aharonov-Casher effect, and the device may be useful as a qubit for quantum computation.
Majorana fermions and a topological phase transition in semiconductor-superconductor heterostructures.
The measurement of the supercurrent through the junction allows one to discern topologically distinct phases and observe a topological phase transition by simply changing the in-plane magnetic field or the gate voltage, which will be a direct demonstration of the existence of Majorana particles.
Generic new platform for topological quantum computation using semiconductor heterostructures.
The heterostructure proposed is a semiconducting thin film sandwiched between an s-wave superconductor and a magnetic insulator which can be used as the platform for topological quantum computation by virtue of the existence of non-Abelian Majorana fermions.