1,096 research outputs found
Measurement-device-independent quantum cryptography
In theory, quantum key distribution (QKD) provides information-theoretic
security based on the laws of physics. Owing to the imperfections of real-life
implementations, however, there is a big gap between the theory and practice of
QKD, which has been recently exploited by several quantum hacking activities.
To fill this gap, a novel approach, called measurement-device-independent QKD
(mdiQKD), has been proposed. It can remove all side-channels from the
measurement unit, arguably the most vulnerable part in QKD systems, thus
offering a clear avenue towards secure QKD realisations. Here, we review the
latest developments in the framework of mdiQKD, together with its assumptions,
strengths and weaknesses.Comment: An invited review to the special issue of the IEEE Journal of
Selected Topics in Quantum Electronics (JSTQE) on 'Quantum communication and
cryptography
Measurement Device Independent Quantum Dialogue
Very recently, the experimental demonstration of Quantum Secure Direct
Communication (QSDC) with state-of-the-art atomic quantum memory has been
reported (Phys. Rev. Lett., 2017). Quantum Dialogue (QD) falls under QSDC where
the secrete messages are communicated simultaneously between two legitimate
parties. The successful experimental demonstration of QSDC opens up the
possibilities for practical implementation of QD protocols. Thus, it is
necessary to analyze the practical security issues of QD protocols for future
implementation. Since the very first proposal for QD by Nguyen (Phys. Lett. A,
2004) a large number of variants and extensions have been presented till date.
However, all of those leak half of the secret bits to the adversary through
classical communications of the measurement results. In this direction,
motivated by the idea of Lo et al. (Phys. Rev. Lett., 2012), we propose a
Measurement Device Independent Quantum Dialogue (MDI-QD) scheme which is
resistant to such information leakage as well as side channel attacks. In the
proposed protocol, Alice and Bob, two legitimate parties, are allowed to
prepare the states only. The states are measured by an untrusted third party
(UTP) who may himself behave as an adversary. We show that our protocol is
secure under this adversarial model. The current protocol does not require any
quantum memory and thus it is inherently robust against memory attacks. Such
robustness might not be guaranteed in the QSDC protocol with quantum memory
(Phys. Rev. Lett., 2017)
Measurement-device-independent verification of channel steering
Extending the concept of steerability for quantum states, channel
steerability is an ability to remotely control the given channel from a
coherently extended party. Verification of channel steering can be understood
as certifying coherence of the channel in an one-sided-device-independent
manner with respect to a bystander. Here we propose a method to verify channel
steering in a measurement-device-independent way. To do this, we first obtain
Choi matrices from given channels and use canonical method of
measurement-device-independent verification of quantum steering. As a
consequence, exploiting channel-state duality which interconverts steerability
of channels and that of states, channel steering is verified. We further
analyze the effect of imperfect preparation of entangled states used in the
verification protocol, and find that threshold of the undesired noise that we
can tolerate is bounded from below by steering robustness.Comment: 8 pages, 2 figure
Measurement-Device-Independent Quantum Secure Direct Communication
Quantum secure direct communication (QSDC) is the technology to transmit
secret information directly through a quantum channel without neither key nor
ciphertext. It provides us with a secure communication structure that is
fundamentally different from the one that we use today. In this Letter, we
report the first measurement-device-independent(MDI) QSDC protocol with
sequences of entangled photon pairs and single photons. It eliminates security
loopholes associated with the measurement device. In addition, the MDI
technique doubles the communication distance compared to those without using
the technique. We also give a protocol with linear optical Bell-basis
measurement, where only two of the four Bell-basis states could be measured.
When the number of qubit in a sequence reduces to 1, the MDI-QSDC protocol
reduces to a deterministic MDI quantum key distribution protocol, which is also
presented in the Letter.Comment: 5 pages, 2 figure
Experimental measurement-device-independent quantum key distribution
Throughout history, every advance in encryption has been defeated by advances
in hacking with severe consequences. Quantum cryptography holds the promise to
end this battle by offering unconditional security when ideal single-photon
sources and detectors are employed. Unfortunately, ideal devices never exist in
practice and device imperfections have become the targets of various attacks.
By developing up-conversion single-photon detectors with high efficiency and
low noise, we build up a measurement-device-independent quantum key
distribution (MDI-QKD) system, which is immune to all hacking strategies on
detection. Meanwhile, we employ the decoy-state method to defeat attacks on
non-ideal source. By closing the loopholes in both source and detection, our
practical system, which generates more than 25 kbit secure key over a 50-km
fiber link, provides an ultimate solution for communication security.Comment: 12 pages, 4 figure
One-sided Measurement-Device-Independent Quantum Key Distribution
Measurement-device-independent quantum key distribution (MDI-QKD) protocol
was proposed to remove all the detector side channel attacks, while its
security relies on the trusted encoding systems. Here we propose a one-sided
MDI-QKD (1SMDI-QKD) protocol, which enjoys detection loophole-free advantage,
and at the same time weakens the state preparation assumption in MDI-QKD. The
1SMDI-QKD can be regarded as a modified MDI-QKD, in which Bob's encoding system
is trusted, while Alice's is uncharacterized. For the practical implementation,
we also provide a scheme by utilizing coherent light source with an analytical
two decoy state estimation method. Simulation with realistic experimental
parameters shows that the protocol has a promising performance, and thus can be
applied to practical QKD applications
Continuous-variable measurement-device-independent multipartite quantum communication
A continuous variable measurement device independent multi-party quantum
communication protocol is investigated in this paper. Utilizing distributed
continuous variable Greenberger-Horne-Zeilinger state, this protocol can
implement both quantum cryptographic conference and quantum secret sharing. We
analyze the security of the protocol against both entangling cloner attack and
coherent attack. Entangling cloner attack is a practical individual attack, and
coherent attack is the optimal attack Eve can implement. Simulation results
show that coherent attack can greatly reduce the secret key rate. Different
kinds of entangled attacks are compared and we finally discuss the optimal
coherent attacks.Comment: 10 pages, 12 figure
Measurement-device-independent QKD with Modified Coherent State
The measurement-device-independent quantum key distribution (MDI-QKD)
protocol has been proposed for the purpose of removing the detector side
channel attacks. Due to the multi-photon events of coherent states sources,
real-life implementations of MDI-QKD protocol must employ decoy states to beat
the photon-number-splitting attack. Decoy states for MDI-QKD based on the weak
coherent states have been studied recently. In this paper, we propose to
perform MDI-QKD protocol with modified coherent states (MCS) sources. We
simulate the performance of MDI-QKD with the decoy states based on MCS sources.
And our simulation indicates that both the secure-key rate and transmission
distance can be improved evidently with MCS sources.The physics behind this
improvement is that the probability of multi-photon events of the MCS is lower
than that of weak coherent states while at the same time the probability of
single-photon is higher
Implementation of a Measurement-Device-Independent Entanglement Witness
Entanglement, the essential resource in quantum information processing,
should be witnessed in many tasks such as quantum computing and quantum
communication. The conventional entanglement witness method, relying on an
idealized implementation of measurements, could wrongly conclude a separable
state to be entangled due to imperfect detections. Inspired by the idea of a
time-shift attack, we construct an attack on the conventional entanglement
witness process and demonstrate that a separable state can be falsely
identified to be entangled. To close such detection loopholes, based on a
recently proposed measurement-device-independent entanglement witness method,
we design and experimentally demonstrate a measurement-device-independent
entanglement witness for a variety of two-qubit states. By the new scheme, we
show that an entanglement witness can be realized without detection loopholes.Comment: 11 pages, 5 figure
Measurement-Device-Independent Twin-Field Quantum Key Distribution
The ultimate aim of quantum key distribution (QKD) is improving the
performance of transmission distance and key generation speed. Unfortunately,
it is believed to be limited by the secret-key capacity of quantum channel
without quantum repeater. Recently, a novel twin-field QKD (TFQKD) [Nature 557,
400 (2018)] is proposed to break through the limit, where the key rate is
proportional to the square-root of channel transmittance. Here, by using the
vacuum and one-photon state as a qubit, we show that the TF-QKD can be regarded
as a measurement-device-independent QKD (MDI-QKD) with single-photon Bell state
measurement. Therefore, the MDI property of TF-QKD can be understood clearly.
Importantly, the universal security proof theories can be directly used for the
TF-QKD, such as BB84, six-state and reference-frame-independent schemes.
Furthermore, we propose a feasible experimental scheme for the
proof-of-principle experimental demonstration.Comment: 29 pages, 4 figures, The security of TF-QKD with single-photon Bell
state measuremen
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