# QUANTUM COMPUTER - Why you should not miss anything about this exotic machine.

*"If you think you understand quantum mechanics, you don't understand quantum mechanics." - Richard Feynman*

Quantum computer is a fast emerging technological discipline that has the potential to transform the way we think about computation and address some of humanity's most challenging and complex problems. Although there are still many obstacles to overcome, it seems evident that quantum computers will play a large part in our future due to the rate at which they are developing and the enormous interest they are receiving from academics, business, and the government.

Let’s understand what Quantum Computer is and why it is different from Classical Computer.

It is a fast-developing technology that leverages quantum mechanical phenomena like superposition and entanglement to manipulate data in order to solve issues that are too complicated for classical computers.

Quantum computer uses the principles of quantum mechanics or quantum theory which explains the **behaviour of energy and material on the atomic and subatomic levels**.

*“The universe is a quantum computer. Since you can simulate any set of particle interactions with a quantum computer made of the same number of particles, then there’s no practical difference between the universe and a quantum computer simulating the universe.” - David Walton*

## QUANTUM COMPUTER vs CLASSICAL COMPUTER

### Structure

Compared to classical computers, quantum computers have a simpler design. They lack a processor and memory. A group of superconducting qubits are used in quantum computers.

### Processing Power

Quantum computers process information differently than classical computers. A quantum computer uses qubits to carry out multidimensional quantum computations. Their processing power increases exponentially with the number of qubits added that mean a connected group of them can provide way more processing power than the same number of binary bits. In other case, bits are used by classical computers to execute various programs. Their power increases linearly with the number of bits added which is substantially less computing power.

### Speed

In comparison to a classical supercomputer, a quantum computer is many times faster. According to reports, Google’s in development quantum computer ‘Sycamore' is said to have performed a computation in 200 seconds as opposed to the 10,000 years it would have taken by one of the fastest super computers in the world i.e. IBM's Summit. By claiming that its supercomputer could complete the calculation in just 2.5 days, IBM disputed Google's assertion. Even though, that is still 1000 times slower than Google's quantum computer.

### General tasks versus Optimization tasks

For routine operations, classical computers perform well and have low error rates. For example, performing simulations, evaluating data for chemical or pharmacological trials, and developing energy-efficient batteries are all tasks that quantum computers are best suited for. However, they are prone to have high error rates.

### Temperature

Classical computers don't require extra-special maintenance. They could use a simple internal fan to avoid overheating. Quantum processors must be insulated from even the slightest vibrations and preserved at absolute zero temperatures. For that, super-cooled super fluids must be used.

Superconducting circuits are used by multiple companies, including IBM, Google, and Rigetti Computing, which are chilled to temperatures colder than deep space. Others, like IonQ, use ultra-high vacuum chambers to trap individual atoms in electromagnetic fields on silicon chips. The objective is to isolate the qubits in a regulated quantum state in both scenarios.

### Size

Quantum computers are more elegant and energy-efficient than supercomputers. An IBM Quantum processor is around the size of a laptop's wafer. The size of a car, a quantum hardware system is mostly made up of cooling mechanisms to keep the superconducting processor at its extremely low working temperature.

### Cost

Compared to classical computers, quantum computers are more expensive and challenging to build.

Building a quantum computer takes a lot of effort and resources. Google has invested billions of dollars and years into developing a quantum computer. By 2029, it hopes to have its quantum computer operational. By 2023, IBM wants to have a 1,000-qubit quantum computer operational. Shenzhen SpinQ Technology, based in China, intends to market a $5,000 desktop quantum computer to consumers for use in schools and colleges. They already began offering a quantum computer for $50,000.

### Processing Logic (Bits vs Qubits)

Classical computing depends on concepts from Boolean algebra and typically uses the **logic-gate approach**. Data must always be handled in an exclusive binary state, with 0 for off and 1 for on. Bits are a sequence of electrical or optical pulses that represent 1s or 0s. At any given time, millions of transistors and capacitors in the core of computer can only be in one state. The speed at which these devices can change states is a constraint. In order to encode information in bits, classical computers nowadays use a binary stream of electrical impulses (1 and 0). This way of processing restricts their ability as compared to quantum computing.

In contrast, the **two-mode logic gate** **approach** used by quantum computers, such as XOR and QO1, allows them to convert 0 into a superposition of 0 and 1 called as **Quantum bits**, or **“qubits”** (1 | 0). Particles like electrons or photons may be utilised in a quantum computer with a charge or polarization that serves as a representation of the numbers 0 and 1. The absurd thing is that qubits can also acquire a mixed state known as a "superposition" in which they are simultaneously 1 and 0. The capability of quantum computing is fundamentally dependent on this ambiguity—the capacity to simultaneously “be” and “not be”. Theoretically, connected qubits can accelerate calculations that would often take millions of years by taking advantage of interference between their wave-like quantum states.

The fundamental physics principle underpinning the uncertainty principle and the reasons why electrons are present everywhere are explained in the video below.

### PROCESS OF MAKING A QUBIT?

A substance capable of achieving a quantum superposition between two states is required to create a qubit.

An example of a qubit is an atomic nucleus. With respect to a magnetic field, the direction of its magnetic moment, or its "spin," might point in either the up or down direction.

Placing and then dealing with that one atom is the difficult part.

• In one research, atomic qubits were created by positioning a single phosphorus atom at a known position inside a silicon crystal.

• The atom might also be made into an ion by losing one of its electrons. The ion can then be fired at with lasers to modify its state after being suspended in free space using electromagnetic fields. This results in a quantum computer with "trapped ions."

• A current in a loop of superconducting metal can also be in a superposition (between clockwise and anticlockwise), resembling a little treadmill that is simultaneously moving forward and backward.

• A light photon may be superposed in the direction it is moving. A maze of optical fibers and mirrors has been used by some researchers to assemble quantum circuits.

#### How is the superposition made?

Have you ever attempted to precisely balance a coin on its edge? That is how it feels to program a qubit. It entails altering a qubit in a way that makes it appear to be "balanced" between states.

This may be accomplished by zapping the atomic nucleus with an electric or magnetic field, which would leave it with an equal chance of spinning either direction.

#### How can the ability of qubits to simultaneously be 0 and 1 enable for speedier computations?

Technically "Both 0 and 1 at the same time" is not qubits. A qubit is continuous ranges of potential values in two dimensions, which are comparable to the points on a unit sphere (such as latitude and longitude or the angles θ and ϕ ), exist at any given time. These two numbers determine the likelihood that a measurement on a qubit will return a 0 or a 1.

A quantum computer does not always make computation "faster." The important thing to remember is that qubits can hold a lot more data than classical bits can. The fact that qubits can be *entangled* (form a group) accounts for a large portion of this data storage capacity rather than individual qubits. Qubits that are entangled have more degrees of freedom than individual qubits do.

While a qubit does have the concepts of 0 and 1, it also has the elusive idea of in-between. That is the main idea of **superposition**. To understand this, consider the sphere-based qubit diagram above.

Formally, this is known as the Block Sphere. The state of a given qubit is expressed as its position on the sphere and is better thought of as a vector rather than a simple 0 or 1 state.

The Block sphere's states are denoted as |0> for the top pole, |1> for the bottom pole, and (I won't get into the math here) (|0> + |1>) / √2 for the middle .i.e., both 0 and 1 at once. **The qubit is not really in both states at once; rather, it is intermediate or indeterminate.**

## HOW DO QUANTUM COMPUTERS WORK?

Let’s understand these fundamental terms:

### Decoherence

Decoherence occurs when the delicate quantum properties of qubits degrade. Factors like vibrations and temperature fluctuations can instantly disrupt the quantum state, causing qubits to lose their superposition and introduce computational errors. To safeguard qubits from such interference, measures like supercooled refrigerators, insulation, vacuum chambers, superconducting circuits, trapped ions, and nitrogen-vacancy centers in diamonds are employed.

Additionally, other sources of decoherence exist, such as quantum gates and the lattice vibrations and background thermonuclear spin within the physical system utilized for implementing the qubits. Decoherence, being effectively non-unitary, is irreversible and must be carefully controlled or avoided.

### Superfluids

While your regular desktop computer employs fans for cooling, quantum processors require an extremely low temperature, just a hundredth of a degree above absolute zero. To achieve this, quantum computer companies employ supercooled superfluids, which facilitate the creation of superconductors.

### Superconductors

At such ultra-low temperatures, specific materials within quantum computer processors exhibit a significant quantum mechanical effect: electrons move through them without encountering any resistance. This property makes them "superconductors."

When electrons traverse superconductors, they form "Cooper pairs," which can carry charge across barriers or insulators through a phenomenon known as **quantum tunnelling.**

### Superposition (1 and 0 at the same time)

Qubits possess the ability to represent multiple combinations of 1 and 0 simultaneously. This remarkable characteristic is called superposition. Researchers achieve superposition by manipulating qubits using precision lasers or microwave beams.

According to IBM, the true significance lies in what a qubit can do, rather than what it is. A qubit places the quantum information it contains into a state of superposition, encompassing all possible configurations of the qubit. Groups of qubits in superposition create intricate, multidimensional computational spaces, enabling the representation of complex problems in novel ways.

Leveraging this counterintuitive phenomenon, a quantum computer with multiple qubits in superposition can explore an enormous number of potential outcomes concurrently. The final result of a calculation only emerges upon measuring the qubits, which instantaneously collapses their quantum state to either 1 or 0.

**THIS IS THE PHENOMENON USED AS BASIS OF THIS BLOG “Quantum Thinking“.**

*“Quantum physics thus reveals a basic oneness of the universe.” - Erwin Schrodinger*

### Entanglement

Entanglement is a quantum mechanical phenomenon that correlates the behavior of two distinct entities. When two qubits are entangled, changing the state of one qubit instantaneously and predictably alters the state of the other, even if they are separated by vast distances. Quantum algorithms leverage these relationships to find solutions to complex problems.

The exact mechanism and underlying reasons for entanglement remain mysterious, even baffling Einstein, who famously referred to it as "**spooky action at a distance**." Nevertheless, entanglement plays a crucial role in the power of quantum computers. In classical computers, doubling the number of bits simply doubles the processing power. However, thanks to entanglement, adding extra qubits to a quantum machine results in an exponential increase in its computational capabilities.

*“Our brains are too slow to register that every concrete object is winking in and out of existence at the quantum level thousands of times per second.” - Deepak Chopra*

### Quantum Algorithms

Quantum algorithms are specifically designed to harness the unique properties of qubits. Among these algorithms, **Shor's algorithm** stands out as one of the most renowned. It possesses the remarkable ability to factor large numbers exponentially faster than the most efficient classical algorithms known to date. This breakthrough holds significant implications for cryptography since many encryption methods rely on the difficulty of factoring large numbers.

Another noteworthy quantum algorithm is **Grover's algorithm**, which tackles the task of searching an unsorted database containing N items. Classical algorithms require O(N) time for this task, while Grover's algorithm accomplishes it in O(√N) time. This characteristic makes quantum computers particularly well-suited for specific optimization problems and pattern matching endeavors.

**IBM explained Quantum Computer Working**

## WHAT IS QUANTUM THEORY?

The development of quantum theory commenced in 1900 when German physicist Max Planck delivered a presentation to the German Physical Society. Planck **introduced the concept that energy and matter exist in individual units**, rather than being continuous waves. Over the subsequent three decades, several scientists contributed to the advancements that led to our modern understanding of quantum theory.

Key elements of quantum theory encompass the following:

• Similar to matter, energy is composed of distinct units, rather than being continuous in nature.

• Under specific conditions, elementary particles exhibit characteristics of both particles and waves.

• Movement of elementary particles is inherently random, making it fundamentally unpredictable.

• Simultaneously measuring two complementary properties of a particle, such as its position and momentum, is subject to flaws. The more precisely one property is measured, the more imprecise the measurement of the other property becomes.

*“Anyone not shocked by quantum mechanics has not yet understood it.” - Niels Bohr*

*“What quantum physics teaches us is that everything we thought was physical is not physical.” - Bruce H. Lipton*

*“Common sense has no place in Quantum Mechanics.” - Michio Kaku*

## BENEFITS OF QUANTUM COMPUTER

Quantum computer has the potential to offer the following benefits:

**Speed.**Quantum computers exhibit extraordinary speed when compared to classical computers. For instance, they can significantly accelerate financial portfolio management models like the Monte Carlo method, which assesses outcome probabilities and associated risks.**Solving complexity.**Quantum computers are specifically designed to handle complex calculations simultaneously. This capability is particularly valuable for factorizations, which could contribute to the development of decryption technologies.**Simulations.**Quantum computers excel at running intricate simulations, surpassing the capabilities of classical computers. They can prove invaluable in conducting molecular simulations, which play a vital role in prescription drug development.**Optimization.**With their immense processing power, quantum computers have the potential to transform artificial intelligence and machine learning. They can effectively handle vast amounts of complex data, facilitating enhanced optimization techniques.

## LIMITATIONS OF QUANTUM COMPUTER

Despite promising benefits, there are still huge limitations to overcome:

**Interference.**Quantum systems are highly sensitive, and even the slightest disturbance can lead to decoherence, causing quantum computations to collapse. Isolation from external interference is crucial during the computation phase. Promising progress has been made by employing qubits within intense magnetic fields.**Error correction.**Unlike traditional digital bits, qubits cannot utilize conventional error correction methods. Error correction is of utmost importance in quantum computing, as a single error can render an entire computation invalid. Encouragingly, significant advancements have been made, including the development of error correction algorithms utilizing multiple qubits.**Output observance.**Extracting output data after a quantum calculation risks corrupting the data itself. Special*wave*shape inherent of the probability curves in quantum computers can be employed in database search algorithms, circumventing this challenge. By ensuring correct measurements once all calculations are completed, the quantum state can decohere into the accurate answer.

## USES OF QUANTUM COMPUTERS

Supercomputers aren't all that super for some issues. Supercomputers are used by scientists and engineers when they are faced with challenging tasks. These are **enormous classical computers that frequently have thousands of cores for both the CPU and GPU.** However, some types of issues are difficult for even supercomputers to solve.

When a supercomputer struggles, it's often because the large classical machine was given a challenging problem to answer. Complexity is frequently the cause of failure for classical computers.

**Complex Problems** are problems where multiple variables that interact in intricate ways are considered. Examples include:

• Simulating or modelling the behaviour of individual atoms inside a molecule due to the interactions between the various electrons.

• Sorting out the ideal routes for a few hundred tankers in a global shipping network.

• Auto-makers simulate the chemical composition of electrical-vehicle batteries to help find new ways to improve their performance.

• Pharmaceutical companies are leveraging them to analyse and compare compounds that could lead to the creation of new drugs.

• Aircraft manufacturer, for instance, is using them to help calculate the most fuel-efficient ascent and descent paths for aircraft.

• One Auto maker has unveiled a service that calculates the optimal routes for buses and taxis in cities in order to minimize congestion.

• Financial institutions may be able to use quantum computing to create investment portfolios for retail and institutional clients that are more effective and efficient. They may concentrate on enhancing fraud detection and developing better trading simulators.

• Healthcare sector can create novel medications and genetically personalized treatments. It might also power more advanced DNA research.

• For stronger internet security, quantum computing can assist in developing better data encryption and ways to use light signals to detect hackers in the system.

## QUANTUM BIOLOGY

Quantum biology investigates how quantum effects affect biological functions, with the potential to advance biotechnology and medicine. Despite the widespread belief that quantum effects quickly vanish in biological systems, research indicates that these effects are crucial to physiological functions. This opens the door to the creation of non-intrusive, remote-controlled therapeutic devices by altering these processes. But to do this, scientific research must adopt a novel, interdisciplinary strategy.

Consider utilizing your smartphone to regulate your own cells' activity to treat illnesses and injuries. It sounds like something out of a sci-fi author's excessively hopeful imagination. But thanks to the developing study of quantum biology, this might be a reality in the future.

## QUANTUM SUPERMACY

It's the point at which a quantum computer can successfully accomplish a mathematical operation that is clearly beyond the capabilities of even the most powerful supercomputer.

Due to the fact that researchers are always developing new algorithms to improve the performance of classical machines and the advancement of supercomputing hardware, it is still uncertain exactly how many qubits will be required to achieve this. But in order to win the title, academics and businesses are working hard and conducting tests against some of the most potent supercomputers.

## PLAYERS IN QUANTUM COMPUTER MARKET

The creation of quantum computers has advanced significantly in recent years. Large-scale quantum computers have been constructed by corporations like IBM, Google, and Alibaba, and they are now accessible to academics and developers via the cloud.

This has sparked a surge in interest in quantum computing and given rise to a burgeoning community of scientists and programmers who are investigating the possibilities of this novel technology. Additionally, governments and companies from all over the world are spending extensively in quantum computing research due to the technology's potential to revolutionize a variety of areas and sectors.

## TL; DR

• Quantum computing makes use of quantum physics phenomena to develop new techniques.

• Qubits are used in quantum computing.

• A qubit can exist in a multidimensional state in contrast to a standard computer bit, which can only be either 0 or 1.

• With additional qubits, quantum computers' power increases exponentially.

• Power of classical computers can only grow linearly as more bits are added.

## CONCLUSION

For many years, the full potential of quantum computers might not be realized. However, universities and companies working on them are struggling to find qualified researchers in the subject, as well as suppliers of some essential parts. But if these exotic computing devices live up to their promise, they have the potential to alter entire industries and accelerate global innovation.

*“Nature at a fundamental level works in a quantum way." - Sundar Pichai*

*“The history of the universe is, in effect, a huge and ongoing quantum computation. The universe is a quantum computer.” - Seth Lloyd*

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