We are observing in this pandemic situation of COVID-19 the world in very challenging and to solve this complex problem in quick time. Today, we are facing a difficult complex problem such as Coronavirus. This Coronavirus affects human life. Quantum computing is the only support that can give us quick results by processing the Coronavirus compound at high computation speed. Whatever present circuits in VLSI domain, we cannot perform the high-speed computation and not tackle the complex case as present COVID-19. In this article, we have been discussed about quantumcomputing era during the pandemic situation ofCOVID-19. Further, this paper presents fundamental about quantum properties such as superpo- sition, entanglement, and quantum programming tools such as Qiskit (IBM), pyQuil (Google), ProjectQ (ETH), Revkit, and RCvewier + . We have presented quantum circuit and its decomposed circuit of such gates as Toffoli, Fredkin, Peres, and new fault tolerance. In addition, we proposed algorithm as transforming cascade to the quantumcircuitwhich is extended for verification based.All these concepts presented here will be very useful to researcher, academician, and industry person to tackle this pandemic situation of COVID-19.

1. Chapter 46
Concept and Algorithm of Quantum
Computing During Pandemic Situation
of COVID-19
Nirupma Pathak, Neeraj Kumar Misra, Bandan Kumar Bhoi,
and Santosh Kumar
Abstract We are observing in this pandemic situation of COVID-19 the world in
very challenging and to solve this complex problem in quick time. Today, we are
facing a difficult complex problem such as Coronavirus. This Coronavirus affects
human life. Quantum computing is the only support that can give us quick results
by processing the Coronavirus compound at high computation speed. Whatever
present circuits in VLSI domain, we cannot perform the high-speed computation
and not tackle the complex case as present COVID-19. In this article, we have been
discussed about quantum computing era during the pandemic situation of COVID-19.
Further, this paper presents fundamental about quantum properties such as superpo-
sition, entanglement, and quantum programming tools such as Qiskit (IBM), pyQuil
(Google), ProjectQ (ETH), Revkit, and RCvewier + . We have presented quantum
circuit and its decomposed circuit of such gates as Toffoli, Fredkin, Peres, and new
fault tolerance. In addition, we proposed algorithm as transforming cascade to the
quantumcircuitwhichisextendedforverificationbased.Alltheseconceptspresented
here will be very useful to researcher, academician, and industry person to tackle this
pandemic situation of COVID-19.
46.1 Introduction
The structure of Coronavirus is in the spherical shape and diameter of 100 nm [1]. Due
tothesmallstructureofCoronavirus,wehavetoresorttoahighcomputationpotential
N. Pathak · S. Kumar
Department of Computer Science and Engineering, Maharishi University of Information
Technology, Lucknow, Uttar Pradesh 226013, India
N. K. Misra (B)
Department of Electronics and Communication Engineering, Bharat Institute of Engineering and
Technology, Hyderabad 501510, India
B. K. Bhoi
Department of Electronics and Telecommunication, Veer Surendra Sai University of Technology,
Burla 768018, India
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022
A. K. Somani et al. (eds.), Smart Systems: Innovations in Computing,
Smart Innovation, Systems and Technologies 235,
https://doi.org/10.1007/978-981-16-2877-1_48
523

2. 524 N. Pathak et al.
like quantum computing. Quantum computing is an area that can handle a pandemic
situation of COVID-19 [2]. To study this small compound of coronavirus, we will
need a supercomputer or powerful computer that process the complex function with
very high speed [3]. This powerful supercomputer will study the protein structures.
As we are getting into this pandemic situation, we have to solve the COVID-19
problem by using an interdisciplinary approach and the latest technology [3]. As
we know that COVID-19 is a problem, it is an exponential it could be even more
complex in future [4]. To solve this exponential problem, we have to use a quantum
computer to solve the exponential problem in high computation speed [5].
A new paradigm of quantum computing during pandemic situation of COVID-19
has been presented with these main contributions.
• We present the basic concepts that can solve COIVD-19 problem in the era of
quantum computing.
• We discuss quantum computing two superpower states using it we can solve an
exponential problem like COVID-19
• We demonstrate the programming of quantum computers such as Qiskit (IBM),
pyQuil (Google), and ProjectQ (ETH),
• We demonstrate the programmable features of quantum circuit design and analysis
tool as Revkit, RCViewer+.
• We present the basic quantum gates into decomposition gates using programmable
quantum gates
• We propose an algorithm as transforming cascade to the quantum circuit. The
presented algorithm is verified by cascading of F2G and PG gates.
46.2 The Basic Aspect of Quantum Computing
We are observing that in this pandemic situation, we are resorting to the digital
computer that is working on the binary digits. We also have another computation
potential like quantum computer which is working on the Qubit [5]. As we come to
the qubit era world, we see that quantum computing is the best solution to solve the
exponential problem like COVID-19. If we see the computational power inside the
qubit which is the fast computing for huge data [6]. Qubit is the unit which gives
information in the quantum computing world.
46.2.1 Quantum Computing Principle States
Classical computers are work in binary digits such as 0 and 1. We can do these easy
problems with classical computers; but if there is a complex problem that is COVID-
19, we have to resort to quantum electronics era. As we see there is a COVID-19
virus in our nature, this is exponential problems. Quantum computing is the era
to tackle this exponential problem easily. As we go to some fundamental in the

3. 46 Concept and Algorithm of Quantum Computing … 525
quantum computing, we observe that quantum computing has two superpower states
as entanglement and superposition [7].
46.2.1.1 Superposition
In quantum computing, superposition is a property that tells multiple states at the
same time that can be anywhere and can be combined.
46.2.1.2 Entanglement
Entanglement is a property in the quantum computing world that makes the correla-
tion between quantum particles. Entanglement and superposition are two properties
in the quantum computing world that can perform the vast number of calculation
as fast as well as simultaneously [8]. We can analyze its COVID-19 compound in
the fast-way by using entanglement and superposition properties. If we look at the
classical digital computers, it is only on the binary digits like 1 and 0. If we see
the advantage of quantum computing, it is also processing by binary 1 and 0 and
superposition of 1 and 0. In classical computing, we cannot process the complex
tasks, but we can solve it by moving it to quantum computing era. If we look as
novel COVID-19, it is a complex compound here some different things are mixed in
it not like normal, so we can use the entanglement and superposition properties of
quantum computing to compute and analyze fast [9].
46.2.2 Qubit
Quantum computing does not binary digit which is a new unit like a qubit. In quantum
computing, there is no such state like 1 or 0 as in classical computers, here the
superposition of those classical states [10]. In a more formal way, qubit can exist as
1 and 0 or simultaneously as combined 1 and 0 with vector coefficient delegacy the
probability for each other. If we see in physical science, qubit can be projected by
the spin of the electron may be +1/2 and −1/2 based on orientation. Qubit has two
states like 1 and 0, which are associated with two number of eigenstates of the spin
of an electron as the below equations.
|0 = |↓, |1 = |↑, |0 + |1 = |↓ + |↑

4. 526 N. Pathak et al.
46.2.3 Concept of Thermodynamic in Quantum Computing
There is no information loss in the system then this concept of thermodynamic or
closed system utilize in quantum computing. A property always holds in quantum
gates is the information not erase. [11] If we see in a practical way in the digital
computer system, lots of information erase and heat dissipate inside. Whatever the
basic gates are in the digital computers like AND, NAND, NOR, Ex-OR, and OR,
it has the property that the information is always erased and the heat dissipate. All
the digital logic gates are information erase and heat generated. A famous scientist
Bennett has pointed that in quantum circuits are capable of information lossless.
All the quantum circuits can compute both forward and backwards direction and
hold all the inputs and output information based on the reversibility features [11].
When the forward computation is complete, our inputs information is restored in
the backwards computation. The property of reversible systems has forwards and
backward computation without erasing any information.
46.2.4 Quantum Computing Gates
Some prerequisite is there to synthesize a quantum circuit that we have covered
in this section. Quantum computing and reversible computing are interconnected;
in quantum circuits, all the gates must be reversible. The reversible gate has the
property does not lose the information based on the bijective mapping between
input and output. In the quantum electronics era, a qubit is a basic measurement
of information, whereas in conventional computer, basic unit of information is bits
like ‘1’ and ‘0.’ Some of the basic logic gates are presented in Fig. 46.1. To process
the qubit, we need some quantum circuits using some quantum gates like Toffoli
gate, Fredkin gate, and double Feynman gate. The existing reversible gates such
as Feynman double gate (F2G), Fredkin gate (FRG), Toffoli gate (TG), Feynman
gate (FG), and Peres gate (PG) have attracted the researcher’s attention during last
four decades for the synthesis and optimization of various kind of circuits [12, 13].
Fig. 46.1 Classical
computer gates
AND NAND
Ex-OR Ex-NOR
OR NOR
INVERTER

5. 46 Concept and Algorithm of Quantum Computing … 527
Table 46.1 Existing quantum gates
.v A,B,C
.i A,B,C
.o A,B,C
BEGIN
T3 A,B,C
END
Toffoli.tfc
.v A,B,C
.i A,B,C
.o A,B,C
BEGIN
T3 A,B,C
T2 A,C
END
PG.tfc
.v A,B,C
.i A,B,C
.o A,B,C
BEGIN
T2 C,B
T3 A,B,C
T2 C,B
END
FRG.tfc
.v A,B,C
.i A,B,C
.o A,B,C
BEGIN
T2 A,B
T2 A,C
END
F2G.tfc
1 2
1 2 3 4 5
1 2 3 4
1 2 3 4 5
QC=5
QC=4
QC=5
QC=2
Decomposition not possible
Reversible tfc
code realization
of quantum
circuit
Reversible circuit Quantum circuit
F2G
TG
PG
FRG
Table 46.1 shows reversible logic gates codes (use for quantum circuit construction),
reversible circuit, and quantum circuit.
46.2.5 Programming of Quantum Computers
To design any quantum circuit, we need basic reversible gates, programming, and
tool to design point of view. There are the latest tools and devices such as Qiskit
(IBM), pyQuil (Google), ProjectQ (ETH), Revkit, and RCViewer + to design and
compute qubits in quantum computers [14–18].
46.2.5.1 ProjectQ
ProjectQ is an open-source tool started at ETH Zurich that we can use in synthesizing
quantum circuit in quantum computing era. We synthesize quantum circuit through
quantum programs in Python.

6. 528 N. Pathak et al.
46.2.5.2 Qiskit
Qiskit is an open-source tool used in synthesizing the quantum circuit, observing
the circuit, simulating a circuit, unitary backend. Further, it is used as the quantum
circuit error analysis. In this tool, many libraries are available such as standard
gates, Boolean logic circuits gates, many generalized gates, many arithmetic circuits,
adders, comparator, and data encoding circuits. This tool provides with the design
and manipulation of quantum programming and environment like IBM Q in the
system. This tool was developed by IBM research and the initially released date on
March 7, 2017.
46.2.5.3 pyQuil
In this pyQuil, we do quantum programming using the python platform. This pyQuil
has three main tasks. The first tasks as from PyQuil we generate some program
which is used for quantum gates and its operations. Second tasks are quil compiler in
the quantum virtual machine is used for compiling and simulating quil programs in
python. In the third tasks, we can execute a quil program that is like a real quantum
processor as the use of quantum cloud services.
46.2.5.4 Revkit
Revkit is a tool in which we can design a quantum circuit and extract the quantum
parameters as ancilla input, garbage outputs, number of transistors, number of qubits
like one or two, and quantum cost.
Revkit tool design flow for the reversible circuit is summarized as:
(a) To synthesize the reversible circuits, GUI needs to be created in the Revkit-1.3
tool.
(b) The function (*.pla) provide the truth table of the reversible gate. In the embed-
ding, the box is interfaced the *.pla to exact synthesis box. The exact synthesis
box is the next GUI step. The optimal value of circuits cost is achieved by exact
synthesis.
(c) To achieve the reversible circuit and parameter, the circuit viewer and result
boxes are utilized in GUI in Revkit tool.
The complete flow to make this graphical user interface (GUI) is shown in
Fig. 46.2.
46.2.5.5 RCViewer+
RCViewer+ is a tool used in designing reversible circuits and parameters extraction.
Advantage of this tool is that if we have .tfc file then by using .tfc file, we can

7. 46 Concept and Algorithm of Quantum Computing … 529
a b
c
Fig. 46.2 GUI for quantum circuit construction based on Revkit-1.3 tool
decompose the quantum circuit into C-V, C-V+ gates and also phase, H and CNOT
gates as shown in Fig. 46.3. There is an optimization facility in RCViewer+ as
shown in Fig. 46.4. In the optimization process, we combine some quantum gates
and optimal circuit form. The benefit of an optimal circuit is that its performance
parameters are good like quantum cost. The benefit of less quantum cost is that it
will have few count of quantum gates in quantum circuits, and it will less delay from
input to output, and the performance of a circuit will be higher. We have also found
out the number of level in the quantum circuit as shown in Fig. 46.5. Through this
level, we have visualized how many quantum gates involved in the quantum circuit.
A simple procedure of parameters extraction is shown in Fig. 46.6.
Fig. 46.3 Decomposing of Toffoli circuits by RCViewer+

8. 530 N. Pathak et al.
Fig. 46.4 Optimize circuit example by RCViewer+
Fig. 46.5 Manipulation of number of levels by RCViewer+
46.3 Related Work
The structure of novel COVID-19 is nanoscale as shown in Fig. 46.7. We learned
in the literature that IBM has designed a quantum processor using superconductor
material for a qubit [19]. There is a Josephson junction in the quantum processor
because they are very close (100 nm) like the COVID19 virus as shown in Fig. 46.8.
This Josephson junction has a ground state and excited state that looks like the

9. 46 Concept and Algorithm of Quantum Computing … 531
Fig. 46.6 Extraction of parameters by RCViewer+
Fig. 46.7 Novel COVID-19
[19] a nanostructured,
b single-molecule structure
(a)
(b)

10. 532 N. Pathak et al.
Fig. 46.8 Quantum
processor using
superconductor material for
a qubit [19]
quantum computer and holds the different states such as entanglement, interference,
and superposition [20].
Looking at this pandemic situation of COVID-19 that we are getting the strong
motivation to introduce fundamentals of quantum computing and gives everyone to
understand this quantum technology [21–23].
46.4 The Proposed Algorithm Transforming Cascade
to Quantum Circuit
In this section, we have presented a method of cascading the multiple quantum
gates and draw its equivalent quantum circuit based on this proposed algorithm.
This algorithm is named as transforming cascade gates to the quantum circuit. The
detailed description of the transforming-cascaded reversible gate-based circuits into
respective quantum equivalent circuits has summarized in these process as.
Process 1. Prepare individual gate *.tfc code for the quantum gates associated in the
cascaded level of gate. This .tfc code is a quantum programming code which is used
for quantum circuit construction.
Process 2. We assign an alphabetical numbers to all the gates in the quantum circuit
to every nodes. One thing to keep in mind here is that whatever alphabetical number
on the output node, we have to put same as well on inputs.

11. 46 Concept and Algorithm of Quantum Computing … 533
Fig. 46.9 Transforming cascade F2G and PG gates to quantum circuit
Process 3. All the nodes we have to see on the combined gate-level architecture will
be prepared *.tfc code by seeing assigned alphabet numbers.
Process 4. The combined.tfc code for the cascaded gate-level circuit is obtained
using Rcviewer + tool, ready for decomposition, optimization, and quantum cost
calculation.
Figure 46.9 describes how the cascaded gates are combined after that we get the
quantum circuit. First, we go to the individual gates by generating the .pla code. In this
transforming cascade to quantum circuit algorithm, first of all, we need the .pla code
of the individual reversible gates. After that, we will level or assign some alphabets
to all inputs and outputs by going to the cascaded gates as F2G and PG combined
in Fig. 46.9. As the example in Fig. 46.9 two gates, F2G and PG are combined.
In the cascade gate, we do not change the sequence of alphabets to anyone while
assigning for inputs to outputs. After assigning this level to all the cascaded gates,
we need to generate the .pla file of the cascaded gates. Now we will input this
.pla file in GUI as mentioned in Fig. 46.2, after that, we have to go to simulation
after completing the GUI in Revkit. After this GUI completes, we will extract its
parameters as ancilla input, garbage outputs, number of transistors, number of qubits
like one or two, and quantum cost [24, 25]. This is the complete flow that we can
analyze quantum circuit performance based on parameters such as ancilla input,
garbageoutputs,numberoftransistors,numberofqubitslikeoneortwo,andquantum
cost. To be a good designer, we have to optimize all these parameters minimum.
Optimal parameters have benefit quantum circuits performance will be high and fast
computation. Optimizing these parameters has a good research topic in the quantum
computing era. This transforming algorithm is very useful for quantum circuit’s
construction based on cascade gates. This is an obstacle in research that there is no

12. 534 N. Pathak et al.
Fig. 46.10 Complete
quantum circuit of F2G and
PG
F2G PG
any algorithm for quantum circuit’s construction based on cascade gates; but through
this algorithm, we can design quantum circuits based on cascade gates in an effective
way. The complete quantum circuit of cascade F2G and PG is presented in Fig. 46.10.
46.5 Conclusion
There are some constraints in VLSI MOS devices like short channel effect and body
effect. At present pandemic, COVID-19 situation problem is exponential nature.
Now we have to use emerging technology such as quantum computing that can
solve this exponential nature problem effectively. In this article, we focus on the
COVID-19 exponential problem which has complex. Looking at this pandemic situ-
ation, quantum technology has a capable technology than can solve the complex
problem based on two properties such as superposition and entanglement. COVID-
19 compound structure analysis is required quantum circuit that effectively compute
and analyze. There is no method to bring the cascade gates to the quantum circuit in
state-of-the-artwork.Accordingly,wehavetopresentanewalgorithmthattransforms
complex circuit into a quantum circuit and becomes our work easy. In this article
effective algorithm as transforming cascade gates to the quantum, the circuit has been
introduced successfully. Further, the proposed algorithm discussed has verified by
the cascade of F2G and PG and meet the quantum circuits. In future, this algorithm
is very powerful in terms of transforming cascade gates to the quantum circuit, and
it will helpful for a designer who wants to synthesize any complex quantum circuits
based on cascade gates.
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