# Quantum Computing Explained: Definition, Uses, and Leading Examples

![Quantum Computing: An area of computer science that uses the principles of quantum theory.](https://www.investopedia.com/thmb/mL2a2GAnrskc-ebuq-UT-GM_bwU=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/quantum-computing.asp-FINAL-1-68635090f7534414b9173598fe0ad95c.png)

*— Investopedia / Joules Garcia*

## What Is Quantum Computing?

Quantum computing, a cutting-edge realm of computer science, leverages quantum theory to revolutionize how complex computational problems are tackled. Unlike classical computers, which use electrical impulses in a binary manner (1s and 0s) to process information, quantum computers employ quantum bits, or qubits. These qubits harness subatomic particles—like electrons or photons—to exist in multiple states simultaneously, vastly enhancing computational capabilities. This allows quantum computers to perform calculations that classical computers would find insurmountable within a feasible timeframe.

The exciting potential of quantum computing draws big companies like IBM, Google, and Microsoft, which are working to solve complex problems in finance, healthcare, and aerospace.

### Key Takeaways

*   Quantum computing uses qubits, which can exist in multiple states simultaneously, enabling faster and more complex calculations compared to classical computing.  
    
*   Major companies like Google, IBM, and Microsoft are investing heavily in quantum computing, aiming to provide future cloud-based quantum services.  
    
*   Quantum computing has the potential to revolutionize sectors such as finance, healthcare, and security by significantly enhancing data processing capabilities.  
    
*   Despite its promise, quantum computing faces significant challenges, including maintaining low temperatures and preventing qubit interference.  
    
*   Quantum computers are more expensive and complex to build than classical computers, but they offer exponential increases in processing power as qubits are added.  
    

## Quantum Computing: History and Foundational Concepts

Quantum computing began in the 1980s when experts found that some problems could be solved better with quantum algorithms than with traditional ones.  

Quantum computing can quickly sort through many possibilities to find solutions to tough problems. Where classical computers store information as bits with either 0s or 1s, quantum computers use qubits. Qubits carry information in a quantum state that engages 0 and 1 in a multidimensional way.

This great computing power and expected market size have caught the attention of top companies. These include IBM, Microsoft, Google, D-Wave Quantum, Nokia, Intel, Airbus, HP, Toshiba, Mitsubishi, SK Telecom, NEC, RTX (formerly Raytheon), Lockheed Martin, and Quantinuum.

## Quantum Computing in Action: Applications and Benefits

Quantum computing could greatly impact areas like security, [finance](https://www.investopedia.com/terms/f/finance.asp), military affairs, drug design, aerospace, and manufacturing.

Quantum computers could enhance secure information sharing and improve radars for detecting missiles and aircraft. Another area where quantum computing is expected to help is the environment, and keeping water clean with chemical sensors.  

Here are some potential benefits of quantum computing:

*   Financial institutions may be able to use quantum computing to design more effective and efficient investment portfolios for retail and institutional clients. They could focus on creating better trading simulators and improving fraud detection.
*   The healthcare industry could use quantum computing to develop new drugs and genetically targeted medical care. It could also power more advanced DNA research.
*   Quantum computing can create better data encryption and use light to detect system intruders for stronger online security.
*   Quantum computing can be used to design more efficient, safer aircraft and traffic planning systems.  
    

### 25%

  

The estimated percentage of annual revenue growth in the quantum computing and quantum sensing industries in the near future.

## Key Quantum Features: Superposition and Entanglement Explained

Superposition and entanglement are key physics ideas that support quantum computing. They empower quantum computers to handle operations at speeds exponentially higher than conventional computers and with much less energy consumption.

### Superposition

IBM notes that the remarkable aspect of a qubit is what it can do, not what it is. A qubit places the quantum information that it contains into a state of superposition. This refers to a combination of all possible configurations of the qubit.

### Entanglement

Entanglement is integral to quantum computing power. Qubits can become entangled, meaning they exist in a single shared state. In this state, changing one qubit directly and predictably affects the other.

Quantum algorithms are designed to take advantage of this relationship to solve complex problems. Doubling bits in a classical computer doubles power, but adding qubits exponentially boosts computing ability.

### Decoherence

Decoherence happens when a qubit's quantum behavior deteriorates due to instant disturbances from vibrations or temperature changes. This can cause qubits to fall out of superposition and errors to appear in computing. Qubits need protection from interference using super-cooled refrigerators, insulation, and vacuum chambers.  

## Overcoming Barriers: Challenges in Quantum Computing

Quantum computing offers enormous potential for developments and problem-solving in many industries. However, currently, it has its limitations.

*   Decoherence, or decay, can be caused by the slightest disturbance in the qubit environment. This results in the collapse of computations or errors in them. As noted above, a quantum computer must be protected from all external interference during the computing stage.
*   Error correction during the computing stage hasn't been perfected. That makes computations potentially unreliable. Since qubits aren't digital bits of data, they can't benefit from conventional error correction solutions used by classical computers.
*   Retrieving computational results can corrupt the data. Developments such as a particular database search algorithm that ensures that the act of measurement will cause the quantum state to decohere into the correct answer hold promise.
*   [Security and quantum cryptography](https://www.investopedia.com/can-quantum-computing-revolutionize-crypto-8759455) are not yet fully developed.
*   Scaling issues prevent quantum computers from living up to their potential for impactful use. Researchers are still searching for ways to increase the number of qubits that quantum processors can handle. For example, IBM plans to launch a quantum system that can handle 200 logical qubits by 2029 (systems have generally been capable of fewer than 60 logical qubits).

According to global energy leader Iberdola, "quantum computers must have almost no atmospheric pressure, an ambient temperature close to absolute zero (-273°C) and insulation from the earth's magnetic field to prevent the atoms from moving, colliding with each other, or interacting with the environment."

"In addition, these systems only operate for very short intervals of time, so that the information becomes damaged and cannot be stored, making it even more difficult to recover the data."

## Quantum vs. Classical Computers: Understanding the Differences

Quantum computers have a more basic structure than classical computers. They have no memory or processor. All a quantum computer uses is a set of superconducting qubits.

Quantum computers and classical computers process information differently. A quantum computer uses qubits to run multidimensional quantum algorithms. Their processing power increases exponentially as qubits are added. A classical processor uses bits to operate various programs. Their power increases linearly as more bits are added. Classical computers have much less computing power.

Classical computers are best for everyday tasks and have low error rates. Quantum computers are ideal for higher-level tasks, such as running simulations, analyzing data (e.g., for chemical or drug trials), and creating energy-efficient batteries. They can also have high error rates.

Classical computers don't need extra-special care. They may use a basic internal fan to keep from overheating. Quantum processors need to be protected from the slightest vibrations and must be kept extremely cold. Super-cooled superfluids must be used for that purpose.

Quantum computers are also more expensive and difficult to build than classical computers.

> **Important**
>
> In December 2024, Google demonstrated a quantum computer that can solve a problem in minutes that would take a classical computer 1025 years (10 Septillion).

## Leading the Quantum Race: Key Players and Their Advancements

### Google

Google is spending billions of dollars to build its quantum computer by 2029. The company opened a campus in California called Google AI to help it meet this goal. Once developed, Google could launch a quantum computing service via the cloud.  

### IBM

IBM plans to have a 200-qubit quantum computer in place by 2029. For now, IBM allows access to its machines for those research organizations, universities, and laboratories that are part of its Quantum Network. 

### Microsoft

Microsoft offers companies access to quantum technology via the Azure Quantum platform.

### Others

There’s interest in quantum computing and its technology from financial services firms such as JPMorgan Chase and Visa.

## What Is Quantum Computing in Simplest Terms?

Quantum computing relates to computing performed by a quantum computer. Compared to traditional computing done by a classical computer, a quantum computer should be able to store much more information and operate with more efficient algorithms. This translates to solving extremely complex tasks faster.

## How Much Does a Quantum Computer Cost?

A quantum computer costs millions to build. However, in 2020, China-based Shenzhen SpinQ Technology planned to sell a $5,000 desktop quantum computer to consumers for schools and colleges. The previous year, it had begun selling a quantum computer for $50,000.

## How Fast Is a Quantum Computer?

Certain tasks can be performed thousands of times quicker on a quantum computer than on a traditional one.

## The Bottom Line

Quantum computing represents a significant leap from classical computing by utilizing qubits that exist in multiple states at once, enabling immense speed and power in processing complex problems. This revolutionary technology has the potential to transform industries such as finance, healthcare, and aerospace by tackling tasks that classical computers find too challenging.

Despite current hurdles like maintaining qubits at extremely low temperatures and addressing error correction, innovations from major players like IBM, Google, and Microsoft suggest a promising future for quantum systems. As the technology matures, it is expected to offer unprecedented capabilities to industries requiring high-powered computing solutions.

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