Quantum broadcast channels are the fundamental of quantum network communication.To use the channel efficiently and effectively,it is crucial to know the capacity region of the channel.In this paper,we focus on the capacity region problem of quantum broadcast channel with only one sender and two receivers.According to the quantum entanglement generation theorem,we present and prove the capacity theorems of noisy quantum broadcast channels,including classical-quantum and quantum-quantum capacity region theorems,by which we obtain the capacity region of the quantum broadcast channel with depolarizing noise.
Quantum broadcast channels are the fundamental of quantum network communication.To use the channel efficiently and effectively,it is crucial to know the capacity region of the channel.In this paper,we focus on the capacity region problem of quantum broadcast channel with only one sender and two receivers.According to the quantum entanglement generation theorem,we present and prove the capacity theorems of noisy quantum broadcast channels,including classical-quantum and quantum-quantum capacity region theorems,by which we obtain the capacity region of the quantum broadcast channel with depolarizing noise.
Research on capacity of noisy multiple access quantum channels is the basis of the quantum multi-user communications.According to the classical-quantum entanglement generation theorem and the quantum-quantum entanglement generation theorem,the capacity regions,comprised classical-quantum region and quantum-quantum region,and noisy multiple access quantum channels are deduced in this paper.Then,the theorem is applied to the computation of quantum-quantum capacity region of the multiple access phase-flip channel,and the result The result verifies the theorem,and the quantum-quantum capacity region turns out to be a pentagonal region.For simplicity and generality,we consider the multiple access quantum channels with two senders and one receiver.
We explore the classical communication over quantum channels with one sender and two receivers, or with two senders and one receiver, in both one-shot and asymptotic regimes. First, for the quantum broadcast channel (QBC) and the quantum multi-access channel (QMAC), we study the classical communication assisted by no-signalling and positive-partial-transpose-preserving codes, and obtain efficiently computable one-shot bounds to assess the performance of classical communication. Second, we consider the asymptotic communication capability of communication over the QBC and QMAC. We derive an efficiently computable strong converse bound for the capacity region, which behaves better than the previous semidefinite programming strong converse bound for point-to-point channels. Third, we obtain a converse bound on the one-shot capacity region based on the hypothesis testing divergence between the given channel and a certain class of subchannels. As applications, we analyze the communication performance for some basic network channels, including the classical broadcast channels and a specific class of quantum broadcast channels.
We explore the classical communication over quantum channels with one sender and two receivers, or with two senders and one receiver, First, for the quantum broadcast channel (QBC) and the quantum multi-access channel (QMAC), we study the classical communication assisted by non-signalling and positive-partial-transpose-preserving codes, and obtain efficiently computable one-shot bounds to assess the performance of classical communication. Second, we consider the asymptotic communication capability of communication over the QBC and QMAC. We derive an efficiently computable strong converse bound for the capacity region, which behaves better than the previous semidefinite programming strong converse bound for point-to-point channels. Third, we obtain a converse bound on the one-shot capacity region based on the hypothesis testing divergence between the given channel and a certain class of subchannels. As applications, we analyze the communication performance for some basic network channels, including the classical broadcast channels and a specific class of quantum broadcast channels.
Abstract Quantum broadcast is a method for distributing known quantum information to multiple recipients at once. Although the no-cloning theorem prohibits copying unknown quantum states, it is still possible to transmit the same known state to different destinations. This research introduces two new approaches. The first approach allows a sender to broadcast a single qubit to n receivers using a specialized entangled state known as a 2 n -qubit cluster state. The paper illustrates this method with a detailed example for four receivers ( n = 4 ) and demonstrates its validity through implementation on the Qiskit platform. The second protocol, builds upon the first protocol and allows for broadcasting a particular class of n-qubit state to n receivers. The effects of different quantum noise types on the protocol are investigated, with the fidelity metric used to quantify the quality of broadcasted states over a noisy quantum channel. These new protocols offer more efficient ways to share quantum information, potentially paving the way for improved quantum communication networks and internet.
This chapter introduces the notion of noisy quantum channels , and the different types of “quantum noise” that affect qubit messages passed through such channels. The main types of noisy channel reviewed here are the depolarizing , bit-flip , phase-flip , and bit-phase-flip channels. Then the quantum channel capacity χ is defined through the Holevo–Schumacher–Westmoreland (HSW) theorem. Such a theorem can conceptually be viewed as the elegant quantum counterpart of Shannon's (noisy) channel coding theorem , which was described in Chapter 13. Here, I shall not venture into the complex proof of the HSW theorem but only provide a background illustrating the similarity with its classical counterpart. The resemblance with the channel capacity χ and the Holevo bound , as described in Chapter 21, and with the classical mutual information H ( X ; Y ), as described in Chapter 5, are both discussed. For advanced reference, a hint is provided as to the meaning of the still not fully explored concept of quantum coherent information . Several examples of quantum channel capacity, derived from direct applications of the HSW theorem, along with the solution of the maximization problem, are provided. Noisy quantum channels The notion of “noisiness” in a classical communication channel was first introduced in Chapter 12, when describing channel entropy . Such a channel can be viewed schematically as a probabilistic relation between two random sources, X for the originator, and Y for the recipient.
The depolarizing channel is one of the basic quantum channels.For simplicity and generality, quantum channels with two senders and one receiver are considered to discuss the capacity of the quantum depolarizing channel.Two different capacity regions,classical-quantum region and quantum-quantum re- gion,are deduced in theory for the quantum depolarizing channels with two senders and one receiver.The first region is comprised of the rates at which it is achievable for one sender to transmit classical information, while the other to send quantum information.The other region consists of the rates at which each sender sends quantum information.At the same time,the performance of the quantum multiple access depolarizing channel is analyzed.