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Author
Date
2017Type
- Doctoral Thesis
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Abstract
In recent years superconducting qubits coupled to coplanar transmission line resonators
were developed sufficiently to convincingly be considered a promising candidate for real-
izing a scalable quantum computer.
One of the main advantages of superconducting quantum circuits is the variability of
many of its parameters and the possibility to engineer and fabricate the circuits with high
accuracy. Furthermore, it is possible to make the couplings between its individual con-
stituents (superconducting qubits) on the order of several hundreds of megahertz. Given
typical decoherence rates of the system on the order of one hundred kilohertz, this allows
for fast and high-fidelity quantum operations. It enables the realization of long coherence
times of the system and high-fidelity quantum operations at the same time.
In this thesis, the realization and characterization of important experimental build-
ing blocks of a quantum processor are presented. Moreover, the fundamental concepts of
circuit quantum electrodynamics are discussed. In particular we describe a typical exper-
imental setup as well as the design and fabrication of superconducting quantum circuits.
We investigate two quantum communication protocols with up to four transmon qubits
and carefully characterize its quantum gates in order to achieve high fidelities.
The protocol that we experimentally study first is deterministic quantum teleportation
with real-time quantum feedback. We specifically concentrate on the characterization of
the protocol by quantum process tomography. Furthermore, we investigated an entan-
glement distillation protocol up to the single-shot readout, where two copies of weakly
entangled states are used to achieve higher entanglement on one of the pairs. This proto-
col is specifically interesting as it is using only local operations, classical communication
and measurement. A clear increase of the entanglement by the coherent part of the pro-
tocol is observed with averaged readout, where the entanglement is quantified with the
entanglement measure concurrence and with quantum channel capacities.
The presented techniques and results contribute towards realizing a scalable quantum
computer with superconducting circuits and quantum communication in the microwave
regime. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000195786Publication status
publishedExternal links
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Publisher
ETH ZurichOrganisational unit
03720 - Wallraff, Andreas / Wallraff, Andreas
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ETH Bibliography
yes
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