Hi all,
Tomorrow we will hear from Eloïc Vallée, who did his masters thesis in
conjunction with the Brunner group in Geneva, on "mdiQKD with
assumptions on the states overlap". See below for the abstract. We'll
start at 2pm on zoom: https://ethz.zoom.us/j/362994444.
Best,
Joe
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Title: mdiQKD with assumptions on the states overlap
Abstract:
With the upcoming generation of quantum computers, secure
communications will essentially depend on quantum key distribution
(QKD) algorithms. One of the most promising algorithm is the
measurement-device-independent QKD (mdiQKD), first proposed by Lo,
Curty and Qi in 2012. We explore a modified mdiQKD protocol with a
relaxed assumption on the initial states. The assumption relies on the
overlap between the states and not on the exact characterization of
the states. The protocol is a tripartite prepare-and-measure based
protocol. Two parties prepare states and send them to a connecting
node, which performs a measurement on the joint states. And no
assumption is made on the node's measurement. The protocol is
therefore immune to attack on the third party. A secret key can be
established by verifying the honesty of the measurement at the node
through observed statistics. A positive key rate is found for
different situations and demonstrates the protocol viability.
Hi all,
Tomorrow Zhenning Liu will tell us about his master thesis with Andru,
entitled "Depth-efficient proofs of quantumness". See below for the
abstract.
We start as usual at 2pm on zoom: https://ethz.zoom.us/j/362994444.
Best,
Joe
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Abstract: A proof of quantumness is a type of challenge-response protocol
in which a classical verifier can efficiently certify the quantum advantage
of an untrusted prover. That is, a quantum prover can correctly answer the
verifier's challenges and be accepted, while any polynomial-time classical
prover will be rejected with high probability, based on plausible
computational assumptions. To answer the verifier's challenges, existing
proofs of quantumness typically require the quantum prover to perform a
combination of polynomial-size quantum circuits and measurements.
In this project, we give two proofs of quantumness constructions in which
the prover need only perform constant-depth quantum circuits (and
measurements) together with log-depth classical computation. Our first
construction is a generic compiler that allows us to translate all existing
proofs of quantumness into constant quantum depth versions. Our second
construction is based around the learning with rounding problem and yields
circuits with shorter depth and requiring fewer qubits than the generic
construction. In addition, the second construction also has some robustness
against noise.
Hi all,
Tomorrow we will hear from our guest Raffaele Salvia, from SNS in Pisa, on
his recent work "The classical capacity of quantum channels and the problem
of energy preservation". See below for the abstract. We start at 2pm on
Zoom: https://ethz.zoom.us/j/362994444.
Best,
Joe
%%%%%%
Finding the classical capacity of quantum channels is one of the main open
problems in Quantum Information Theory; it has been solved only for some
special classes of channels. This long-standing problem reveals a
surprising connection with the optimal output entropy problem, which arises
in the theory of quantum energy storage. Through the examples of the qubit
amplitude-damping channel and of continuous variable Gaussian channels, I
will show how this relationship can shed new light on both of the problems.