scholarly journals Enhanced Superdense Coding Over Correlated Amplitude Damping Channel

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 598 ◽  
Author(s):  
Yan–Ling Li ◽  
Dong–Mei Wei ◽  
Chuan–Jin Zu ◽  
Xing Xiao
Keyword(s):  
Quantum Communication ◽  
Weak Measurement ◽  
Quantum Channels ◽  
Superdense Coding ◽  
Amplitude Damping ◽  
Additional Information ◽  
Successful Probability ◽  
Amplitude Damping Channel

Quantum channels with correlated effects are realistic scenarios for the study of noisy quantum communication when the channels are consecutively used. In this paper, superdense coding is reexamined under a correlated amplitude damping (CAD) channel. Two techniques named as weak measurement and environment-assisted measurement are utilized to enhance the capacity of superdense coding. The results show that both of them enable us to battle against the CAD decoherence and improve the capacity with a certain probability. Remarkably, the scheme of environment-assisted measurement always outperforms the scheme of weak measurement in both improving the capacity and successful probability. These notable superiorities could be attributed to the fact that environment-assisted measurement can extract additional information from the environment and thus it performs much better.

Weak measurement for improving the efficiency of remote state preparation in noisy

2018 ◽  
Vol 18 (11&12) ◽  
pp. 975-987
Author(s):  
Ming-Ming Wang ◽  
Zhi-Guo Qu
Keyword(s):  
Communication Systems ◽  
Quantum Communication ◽  
Quantum Noise ◽  
Weak Measurement ◽  
Remote State Preparation ◽  
Amplitude Damping ◽  
Output State ◽  
State Preparation ◽  
Phase Damping ◽  
Bit Flip

Quantum communication provides a new way for transmitting highly sensitive information. But the existence of quantum noise inevitably affects the security and reliability of a quantum communication system. The technique of weak measurement and its reversal measurement (WMRM) has been proposed to suppress the effect of quantum noise, especially, the amplitude-damping noise. Taking a GHZ based remote state preparation (RSP) scheme as an example, we discuss the effect of WMRM for suppressing four types of quantum noise that usually encountered in real-world, i.e., not only the amplitude-damping noise, but also the bit-flip, phase-flip (phase-damping) and depolarizing noise. And we give a quantitative study on how much a quantum output state can be improved by WMRM in noisy environment. It is shown that the technique of WMRM has certain effect for improving the fidelity of the output state in the amplitude-damping noise, and only has little effect for suppressing the depolarizing noise, while has no effect for suppressing the bit-flip and phase-flip (phase-damping) noise. Our result is helpful for improving the efficiency of entanglement-based quantum communication systems in real implementation.

scholarly journals Optimal teleportation via noisy quantum channels without additional qubit resources

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dong-Gil Im ◽  
Chung-Hyun Lee ◽  
Yosep Kim ◽  
Hyunchul Nha ◽  
M. S. Kim ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Quantum Teleportation ◽  
Quantum Communication ◽  
Quantum Noise ◽  
Single Copy ◽  
Entangled State ◽  
Quantum Network ◽  
Quantum Channels ◽  
Maximally Entangled State ◽  
Near Term

AbstractQuantum teleportation exemplifies how the transmission of quantum information starkly differs from that of classical information and serves as a key protocol for quantum communication and quantum computing. While an ideal teleportation protocol requires noiseless quantum channels to share a pure maximally entangled state, the reality is that shared entanglement is often severely degraded due to various decoherence mechanisms. Although the quantum noise induced by the decoherence is indeed a major obstacle to realizing a near-term quantum network or processor with a limited number of qubits, the methodologies considered thus far to address this issue are resource-intensive. Here, we demonstrate a protocol that allows optimal quantum teleportation via noisy quantum channels without additional qubit resources. By analyzing teleportation in the framework of generalized quantum measurement, we optimize the teleportation protocol for noisy quantum channels. In particular, we experimentally demonstrate that our protocol enables to teleport an unknown qubit even via a single copy of an entangled state under strong decoherence that would otherwise preclude any quantum operation. Our work provides a useful methodology for practically coping with decoherence with a limited number of qubits and paves the way for realizing noisy intermediate-scale quantum computing and quantum communication.

Protecting quantum coherence in an open system under non-inertial frames

2017 ◽  
Vol 31 (35) ◽  
pp. 1750336
Author(s):  
Long-Fei Wang ◽  
Ming-Ming Du ◽  
Liu Ye
Keyword(s):  
Open System ◽  
Significant Interaction ◽  
Quantum Coherence ◽  
Weak Measurement ◽  
Entangled State ◽  
Unruh Effect ◽  
Amplitude Damping ◽  
Inertial Frames ◽  
Weak Measurement And Reversal

In this paper, we explore the dynamics and protection of quantum coherence in an open system under non-inertial frames by weak measurement and reversal, and design four strategies to protect the quantum coherence of an initial two-qubit entangled state, when the systems suffer from amplitude damping (AD) channel and one subsystem is under non-inertial frames. In practice, there is no strict inertial frames, decoherence and degradation of the quantum coherence caused by the Unruh effect form acceleration will have a significant interaction, therefore it is important to find some means to protect quantum coherence under non-inertial frames.

scholarly journals Weak Measurement and Two-State-Vector Formalism: Deficit of Momentum Transfer in Scattering Processes

Quanta ◽  
2016 ◽  
Vol 5 (1) ◽  
pp. 61 ◽  
Author(s):  
Chariton Aris Chatzidimitriou-Dreismann
Keyword(s):  
Momentum Transfer ◽  
State Vector ◽  
Quantum Effect ◽  
Weak Measurement ◽  
Additional Information ◽  
Incoherent Neutron Scattering ◽  
Experimental Findings ◽  
Condensed Systems ◽  
Incoherent Neutron ◽  
Small Disturbances

<p>The notions of weak measurement, weak value, and two-state-vector formalism provide a new quantum-theoretical frame for extracting additional information from a system in the limit of small disturbances to its state. Here, we provide an application to the case of two-body scattering with one body weakly interacting with an environment. The direct connection to real scattering experiments is pointed out by making contact with the field of impulsive incoherent neutron scattering from molecules and condensed systems. In particular, we predict a new quantum effect in neutron-atom collisions, namely an observable momentum transfer deficit; or equivalently, a reduction of effective mass below that of the free scattering atom. Two corroborative experimental findings are shortly presented. Implications for current and further experiments are mentioned. An interpretation of this effect and the associated experimental results within conventional theory is currently unavailable.</p><p>Quanta 2016; 5: 61–84.</p>

Performance characterization of Pauli channels assisted by indefinite causal order and post-measurement

2020 ◽  
Vol 20 (15&16) ◽  
pp. 1261-1280
Author(s):  
Francisco Delgado ◽  
Carlos Cardoso-Isidoro
Keyword(s):  
Quantum Channel ◽  
Communication Channel ◽  
Quantum Communication ◽  
Quantum Channels ◽  
Causal Order ◽  
Combined Process ◽  
Performance Characterization ◽  
Output State ◽  
Transmission Of Information

Indefinite causal order has introduced disruptive procedures to improve the fidelity of quantum communication by introducing the superposition of { orders} on a set of quantum channels. It has been applied to several well characterized quantum channels as depolarizing, dephasing and teleportation. This work analyses the behavior of a parametric quantum channel for single qubits expressed in the form of Pauli channels. Combinatorics lets to obtain affordable formulas for the analysis of the output state of the channel when it goes through a certain imperfect quantum communication channel when it is deployed as a redundant application of it under indefinite causal order. In addition, the process exploits post-measurement on the associated control to select certain components of transmission. Then, the fidelity of such outputs is analysed to characterize the generic channel in terms of its parameters. As a result, we get notable enhancement in the transmission of information for well characterized channels due to the combined process: indefinite causal order plus post-measurement.

Superdense Coding and Quantum Teleportation

2006 ◽  
Author(s):  
Phillip Kaye ◽  
Raymond Laflamme ◽  
Michele Mosca
Keyword(s):  
Quantum Teleportation ◽  
Communication Channel ◽  
Quantum Communication ◽  
Communication Protocols ◽  
Bell State ◽  
Third Party ◽  
Classical Communication ◽  
Superdense Coding ◽  
Communication Task ◽  
Epr Pair

We are now ready to look at our first protocols for quantum information. In this section, we examine two communication protocols which can be implemented using the tools we have developed in the preceding sections. These protocols are known as superdense coding and quantum teleportation. Both are inherently quantum: there are no classical protocols which behave in the same way. Both involve two parties who wish to perform some communication task between them. In descriptions of such communication protocols (especially in cryptography), it is very common to name the two parties ‘Alice’ and ‘Bob’, for convenience. We will follow this tradition. We will repeatedly refer to communication channels. A quantum communication channel refers to a communication line (e.g. a fiberoptic cable), which can carry qubits between two remote locations. A classical communication channel is one which can carry classical bits (but not qubits).1 The protocols (like many in quantum communication) require that Alice and Bob initially share an entangled pair of qubits in the Bell state The above Bell state is sometimes referred to as an EPR pair. Such a state would have to be created ahead of time, when the qubits are in a lab together and can be made to interact in a way which will give rise to the entanglement between them. After the state is created, Alice and Bob each take one of the two qubits away with them. Alternatively, a third party could create the EPR pair and give one particle to Alice and the other to Bob. If they are careful not to let them interact with the environment, or any other quantum system, Alice and Bob’s joint state will remain entangled. This entanglement becomes a resource which Alice and Bob can use to achieve protocols such as the following. Suppose Alice wishes to send Bob two classical bits of information. Superdense coding is a way of achieving this task over a quantum channel, requiring only that Alice send one qubit to Bob. Alice and Bob must initially share the Bell state Suppose Alice is in possession of the first qubit and Bob the second qubit.

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