1. Ministry Of Higher Education And Scientific Research
University of Diyala College of Engineering
Communications Engineering Department
Performance of Quantum Repeaters
For Mobile Networks
BY
Saba Hashem Hassan
Maryam Nihad Salem
Roaya Ali Abbas
Supervised By
Dr.Raad Subhi Abboud
3. Quantum Repeater Definition
They are devices that measure the quantum properties of photons when they arrive and
transmit these properties to new photons that are sent in the same direction, which
preserves entanglement and allows it to jump from one repeater to another. However,
this technology is still in its early experimental stages, and it will not enter into
commercial investment for several years Quantum repeaters work in a fundamentally
different way from conventional repeaters. Quantum repeaters are used to transmit
quantum information over long distances. In its simplest form, a quantum repeater works
by generating the entanglement (dashed line) between the repeater (middle) and each of
its (left and right) terminal nodes separately
4. So what is Quantum Teleportation and can it Be
Achieved?
This may sound like science fiction, but it’s a real method that involves transferring the
entire data into a quantum format. This approach is based on a quantum phenomenon
known as “entanglement”. Quantum teleportation is done by creating pairs of entangled
photons, then sending one of each pair to the data transmitter and the other to the
receiver. When Alice receives her entangled photon, she lets it interact with a “memory
qubit” that holds the data she wants to pass on to Bob
5. This interaction causes the state of her photon to change, and because it is
entangled with Bob’s photon, the interaction changes the state of his photon
instantly. In fact, this causes the data in Alice’s memory qubits to be “simulated”
from her photon to Bob’s photon. The graphic below illustrates the process with
some additional details
Figure 1 Achieved Quantum Teleportation
6. The Way The Quantum Repeater Works
The way the quantum repeaters work is conceptually similar to the classical repeating
scheme with amplifiers the transmission distance is divided into segments where the loss is
not large, as shown in the figure.
Figure 2 the Way the Quantum Repeater Works
7. Quantum Repeater Components
Components of a quantum repeater network:
1- the link layer : enumerates connections enabling entanglement between nodes in the
network
2- physical layer,
3- All adjacent stations are also connected by classical links
8. The quantum network comprises :
client nodes :which end users directly access, and repeater nodes, which connect clients
by propagating entanglement through the network. We classify repeater nodes based on
the number of other nodes they connect to: a 4-port and a 3-port repeater are labeled
Figure 3: Quantum Repeater Components
9. All of the quantum circuits in the experiments were designed using IBM’s open-
Source SDK – Quantum Information Science toolkit (QISKIT) in Python. The circuits
were run on IBMQ-16-Melbourne – a real quantum computing Device with 15
superconducting qubits, through back-end access via the cloud. After performing the
experiments, they were error-corrected using QISKIT’s Ignis library and its Error-
Mitigation protocols to remove the effects of measurement- Errors in the results. In
addition, the circuits were also simulated natively
Experiments And Results
10. Fig. 4: The Quantum Repeater scheme for generating long-range entanglement: It begins with splitting the
entire link into a number of segments and placing Repeater stations at these nodes. Multiple entangled pairs
are then generated between adjacent nodes. These shorter links are then purified and entanglement swapping is
performed to create a link twice as long as the original one. These new links are then purified and
entanglement swapping is performed again to create a link four times as long. This continues until
entanglement is generated between the end repeater nodes (Alice and Bob). QISKIT’s ‘QASM Simulator’
with a noise model from QISKIT’s Aer library that mimics the device-noise of IBMQ-16-Melbourne. The
simulation results Provide a reference point to which the device results can be compared
11. Quantum Bit
A qubit or qubit in quantum computing is the unit of quantum information, the
quantum equivalent of a classical bit. A qubit is a two-state quantum system like
the polarization of a photon: here the two states are vertical polarization and
horizontal polarization. In classical systems, a bit can only take one of two states.
Whereas, quantum mechanics allows a qubit to take on a superposition of both
states at the same moment, and this is the fundamental property of quantum
computing
12. Qubit states
Figure 5: Bloch ball to represent qubits
The pure qubit state is a linear superposition of the base state. This
means that a qubit can be represented as a linear combination of
𝛽|1
+
(1) |𝜓 = 𝛼|0
13. Entanglement
One important difference between a quantum bit and a classical bit is that several
qubits can exhibit quantum entanglement Entanglement is a non-local property that
allows a set of qubits to exhibit a higher correlation than is possible in classical
systems. Take, for example, two entangled qubits in the Bell case
1
2
|00 + |11
(
2
)
14. Figure 6 : Entanglement Swapping. Two EPR pairs are generatedand distributed: i) between a source
(Alice) and an intermedi-ate node (Quantum Repeater), and ii) between the intermediatenode and a
destination (Bob). By performing a BSM on theentangled particles at the Quantum Repeater,
entanglement iseventually generated between Alice and Bob
16. Definition OF LTE
In telecommunications, Long-Term Evolution (LTE) is a standard for wireless
broadband communication for mobile devices and data terminals, based on the
GSM/EDGE and UMTS/HSPA technologies. It increases the capacity and speed using
a different radio interface together with core network improvements LTE is the upgrade
path for carriers with both GSM/UMTS networks and CDMA2000 networks. The
different LTE frequencies and bands used in different countries mean that only multi-
band phones are able to use LTE in all countries where it is supported.
17. Is 4G The Same As LTE?
There is a misnomer we should get out of the way: LTE is not 4G. We can look to T-
Mobile as an example. They put 4G on everything they can, but make no claim to LTE.
The benchmark for 4G is also much higher than what we currently see with LTE. That
benchmark of 100Mbit/s is established by the International Telecommunications Union
(ITU) in cooperation with the 3GPP. To give a quick idea of how those measures up to
what you have now, 1000kbps is equal to 1Mbit/s. If you ran a benchmark test on your
phone and did the math, you’d see that the actual 4G standard is about 5-10 times faster
than what you probably see now with “LTE”.
18. In being fair, both GSM and CDMA have made some impressive improvements prior to
any LTE implementation. As GSM relies on moving parcels of information, the HSPA, or
high speed packet access, was the natural progression for them. The difference between
GSM and CDMA is that GSM moves packets of information while CDMA allows users to
“stream” information. Neither is necessarily better, they just operate differently. The
CDMA progression gave us CDMA EV-DO, which like HSPA just sped up the entire
process instead of changing anything. Carriers knew they needed a marketing strategy for
the system updates, so the ITU agreed to let them market it as 4G. Again, while it doesn’t
meet the benchmarks set forth by the ITU and 3GPP, it does represent a huge step forward.
Both agencies respect the advancements as significant, so they allowed them to use the
moniker.
19. How LTE Is Work
LTE changes the current way of transmitting data to the Internet Protocol system.
Instead of transmitting small amounts of data, as CDMA and GSM do, it will transmit
large packets of data and simplify service. Think of it as removing speed bumps from
the roads in your city so you can zoom in faster The main benefit of LTE is that it
reduces data latency i.e. LTE incorporates digital signal processing (DSP) to separate
into better packet data transmission. In short, LTE is a supercharger for your GSM or
CDMA car driving around a city free of speed bumps.
20. Figure 8: System architecture of the proposed PS-UA scheme in PS LTE
system
21. How Does LTE Affect You
First, think about your wallet. As we discussed earlier, we don’t technically have true
4G, but we’re paying for it. Again, pointing to Verizon, they really do have the best
network and the most LTE coverage… but you’re going to pay for it. Upgrading all
those towers and such isn’t free, and you’re really the carrier's only means of revenue.
So, if you want more speed, you’ll have to spend a little more money to get it.
Second, consider your needs. Our phones are pretty robust and will continue to improve,
but LTE is taxing. Faster data invariably means more data, as people will rely on their
mobile devices more and more. So, while really fast data speed is fun, it's also affecting
things like your battery. We don’t have much LTE coverage, and battery life is already an
issue.
22. How Fast Is LTE?
For starters, the quality and speed of your connection varies based on the number of users
and the strength of the signal in your area. According to research from Open Signal, the
leading 25 countries offer several 4G download speeds of 37Mbps with 10Mbps uploads.
The fastest 4G LTE countries boast up to 150 Mbps download speeds on average,
although that’s still a rarity for most consumers. For comparison, older 3G networks can
vary quite widely in their actual results. HSPA networks can peak at around 14 Mbps
download and 6 Mbps upload, but they rarely come close to this. Typically, a good LTE
network is at least 5 to 10 times faster than the best 3G coverage.
24. System Model
The performance of hybrid networks (classical - quantum) using quantum repeaters was
analyzed and compared with the bare quantum repeater network. In the distance, these
repeaters are removed and replaced with the classic base station. Several network metrics
were then evaluated modeling both quantum and hybrid networks, such as latency, data
rate, energy efficiency, scalability, power consumption, and implementation cost. The
results show that hybrid networks can provide faster connectivity, lower cost, lower
required operating cost and higher scalability. On the contrary, the bare quantum repeater
network showed higher data rate and higher power efficiency.
25. Power Consumption Model
To model the energy efficiency of the all quantum network, we first calculate the distance
that is required to be covered, then we calculate how many quantum or classical devices are
required to connect this distance. After that, the cost of both cases will be calculated, then the
energy efficiency. Hence, we have assumed 200Km of distance. For this distance, in all
quantum networks, we evaluate how many quantum repeaters, detectors, memories, central
units are required. In hybrid network, we will assume part of this distance is covered by
classical communications, hence we will add this consumption to the quantum part but
reducing the number of the quantum devices.
