Quantum computing uses the underlying principles of quantum physics to store data and do computations.

For certain type of computations, Quantum computer takes only minutes, which a best supercomputer would have taken days or months to perform.

What is special about Quantum Computer

In our current day to day life, we use classical computer. Our laptop, smartphone can be called as classical computers. They store/encode information in binary “bits”. This bit can be either 1s or 0s.

But in a quantum computer, the basic unit of memory is a quantum bit or qubit.

So, while a bit, or binary digit (used in classical computer) , can have a value either 0 or 1 , a qubit can have a value that is either 0 , 1 or a quantum superposition of 0 and 1.

So, a quantum computer can work with zero and one at the same time, using something that is called superposition quantum states.

Here we need to understand superposition and quantum entanglement

Superposition: It’s the ability of a quantum system to be in multiple states at the same time until it is measured. Superposition allows quantum objects to simultaneously exist in more than one state or location. This means that an object can be in two states at one time while remaining a single object.

This superposition state creates a practically infinite range of possibilities, allowing for incredibly fast simultaneous and parallel calculations.

 

Quantum Entanglement: This is the state when two particle links together even if they are miles apart. It effectively means that these 2 particles share a common quantum state. So, if we observe one particle, information of other entangled particle can be arrived at (even if these 2 particles have lights years distance between them…). On similar note, in entangled system, any action to one of these particles will invariably impact the other particle.

So, in Quantum entanglement, when two atoms are connected, or entangled, even if you have physically separated them. Now, if you change the properties of one of them, the property of another atom also changes instantly.

Qubits are made using physical systems, such as the spin of an electron or the orientation of a photon.

Now with the quantum superposition and quantum entanglement (where qubits are linked together even if they are miles apart), a series of qubits can represent different things/states simultaneously.

In a classical computer, with eight bits, we can represent any number between 0 and 255 (and this applies for quantum computer also).

But in quantum computer, each extra qubits, exponentially increases the numbers, which can be represented. We can safely say that a few hundred entangled qubits would be enough to represent more numbers than there are atoms in the universe.

Quantum computing power grows exponentially with each qubit rather than linearly as in the case of linear bits due to the multi state computational capability of qubits.

So, while a 2-bit register in a classical computer can store only one of four binary configurations (00, 01, 10, or 11) at any given time, a 2-qubit register in a quantum computer can store all four numbers simultaneously, because each qubit represents two values. If more qubits are added, the increased capacity is expanded exponentially.

 

For example, a quantum computer with 1 qubit can simulate 2 classical bits, 2 qubits can simulate 4 classical bits (00,01,10,11), 3 qubits can simulate 8 classical bits (000, 001, 011,111,100,101,110) etc.

Taking this further, it means, 50 qubits can simulate 2^50 classical bits.

This is a big differentiator. In situations where there are many possible combinations, quantum computers can consider them simultaneously.

So, while a classical computer will consider/calculate each of combination in sequential/linear way.

Quantum computer will try to execute all those possible combinations, simultaneously. That’s real parallel processing.

 

Possible usage of quantum computing

As quantum computer (with qubits) can store large numbers of values and can execute on any possible equation in a simultaneous way, it is very good, whenever we are dealing with any optimization problem.

For examples, in case, you are planning a trip to various countries, there are various factors to consider before arriving at an optimal plan.

Just for our understanding, let’s consider that you want to visit 12 cities in Europe, which are located across 8 countries.  These can be factors, which you may want to consider,

1. What is the cheapest transport available between 2 cities.
2. On which days, hotels rates are cheapest in a city.
3. You also wanted to attend, say some special festival in 2 cites, which occurs only on a specific date.
4. You also want to include at least enjoy rail journey to enjoy the panoramic view.
5. You want to make sure that during your visit, weather in that city is pleasant.

If you notice, planning an itinerary, can have many possible paths. For situation/problems like that, quantum computer works best and can arrive at best optimal path in a quick time.

On similar note, to predict, what can be weather tomorrow, various inputs are considered.

Here also, quantum computer can arrive at accurate forecast in a very fast way.

Note that, today, with classical computers also, we can solve these problems. I have given these examples, mainly for our understanding point of view.

But there are many businesses sector, where one need to consider many inputs/variables and arrive at optimal path or solution by taking into account various parallel paths.          So with the ‘parallel processing’ power of Quantum computing, we can solve certain type of problems, very quickly.

These can be the sectors, in which quantum computer can play a big role.

1. Pharmaceuticals

Today, a new drug takes an average of billion dollar and more than 10-15 years, before it reaches the market. R&D team need consider various parameter, drug efficacy, toxicity, correct molecule identification etc. before final drug is approved.

So, here also, there are various paths (input to consider), before a suitable drug can be made. With quantum computer, we can reduce the overall cost as well as time.

2. Chemicals

Here also, Quantum computing can reduce R&D cost, quickly identify new molecule, improve the design of new catalysts and save time for all stakeholders.

3. Automotive and Other Manufacturing plants

This industry can also benefit in R&D, better product design as well as improve the internal working of manufacturing plant. In any manufacturing plant, assemble line consists of various tasks.  If those task and hence if overall assemble line can be optimized, it helps a lot in shortening the cycle time and reduce waste/idle time.

4. Financial Industry

Here Quantum computing can help in portfolio management and overall risk management. On a similar note, it can help the lending industry by considering, borrower’s history/score, lender’s score, project for which work loan is planned (and hence chances of completion of project), collateral which is provided, …and hence arriving at optimal interest rate.

Other possible use cases can involve

1. Power and Grid optimization.
2. Weather forecasting
3. Insurance sector
4. Fraud detection
5. Cyber security
6. Logistics and route/traffic optimization
7. Supply chain & inventory optimization
8. Understanding the various event/phenomena of nature, molecule and sub-molecule level interactions which can lead to breakthroughs in chemistry, biology, healthcare, and nanotechnology.
9. AI and Machine learning.

10.Any planning exercise, which can involve numerous inputs and can involve multiple paths before arriving at final solution.

 

Quantum computing is effective at modelling probabilities and permutations. It’s non-deterministic. So, while in classical physics, we deal with certainty, here we deal with ‘probabilities.

Challenges

As of today, quantum computers are highly sensitive to heats or external atmosphere.

To add to this, electromagnetic fields and collisions with air molecules can cause a qubit to lose its quantum properties. This process, known as quantum decoherence, causes the system to crash.

Today, quantum computing faces evident problems regarding scalability and incoherence.

We can say that Quantum computers are extremely sensitive and require very specific pressure and temperature conditions and insulation to operate correctly.

In case, these quantum computers ( qubits) get exposed to external particles, we got error in measurement.

For this reason, it’s important that Quantum computers are stored at a safe, sealed, and cool place. They should get insulated from earth’s magnetic field or external environment and must have almost no atmospheric pressure.  

We still don’t have a fully error-corrected, fault-tolerant quantum computer.

At the time of writing of this article, we can say that we are still 8-10 years away from getting a fault tolerant Quantum computer.

 

Conclusion

 

Quantum computing is a rapidly emerging technology that harnesses the laws of quantum physics to solve problems too complex for classical computers.

 

 

It works by using the principles of quantum physics (the physics of sub-atomic particles), including quantum entanglement and quantum superposition.

 

With the help of principles like superposition & quantum entanglement, Quantum computing uses a computation method which is very different from traditional method used by classical computers.