Quantum advantage is a milestone in quantum computing. It refers to the ability of a quantum computer to solve problems that are beyond the reach of the most powerful non-quantum computers. Quantum advantage also refers to the ability of a quantum computer to perform operations that the best possible classical computer cannot simulate in a reasonable amount of time. 

The term “quantum advantage” was coined by John Preskill in 2012. The concept dates back to proposals of quantum computing by Yuri Manin in 1980 and Richard Feynman in 1981. 

Currently, no quantum computer can perform a useful task faster, cheaper, or more efficiently than a classical computer. Quantum advantage is still a ways off. 

Examples of proposals to demonstrate quantum supremacy include: 

• The boson sampling proposal of Aaronson and Arkhipov 
• D-Wave’s specialized frustrated cluster loop problems 
• Sampling the output of random quantum circuits

Quantum advantage is the milestone the field of quantum computing is fervently working toward, where a quantum computer can solve problems that are beyond the reach of the most powerful non-quantum, or classical, computers.

Quantum computing has many potential advantages, including: 

• Speed: Quantum computers can perform calculations in seconds that would take supercomputers decades or millennia. 
• Computational power: Quantum computers can provide computational power that traditional computers cannot match. 
• Complex problems: Quantum computers can solve complex problems and run complex simulations. 
• Data processing: Quantum computers can process large quantities of data. 
• Insights: Quantum algorithms can provide insights into data that would be difficult to uncover with classical algorithms. 
• Decisions and predictions: Quantum computing can help make better decisions and predictions. 
• Security: Quantum communication systems are resistant to interception, which offers greater protection for confidential and sensitive information. 

Some other advantages of quantum computing include: 

• Improved scalability 
• More efficient use of resources 
• Supply-chain optimization 
• Production 
• Chemical simulation 
• Optimization 
• Machine learning 
• Innovation acceleration 
• Global collaboration 
• Training and education

There are many ways to build a quantum computer. Some approaches include: 

• Superconducting rings or wires: These need to be kept at very low temperatures. 
• Ion traps: Trap ions in an electric field and fire lasers at them. 
• Solid state spin systems: Dope materials with other materials to create these using electrons. 
• Qubits: Find a spot in a material where quantum properties can be accessed and controlled. 
• Entanglement: The state of one qubit is dependent on the state of another qubit. 

Some platforms built around quantum computers include: Superconducting qubits, Spin qubits, Ion traps, Photonics. 

Vendors are developing a dozen types of qubits based on a range of technologies. These include: Ion trap, Silicon spin, Superconductivity. 

All of these approaches require a lot of expensive kit to operate.

Quantum computing is a multidisciplinary field that uses quantum mechanics to solve complex problems.  It’s based on the idea that subatomic particles can exist in multiple states at the same time. Quantum computers use qubits, or quantum bits, to store and extract information. Unlike classical computers, which can only store 1s or 0s, qubits can store multiple values at once. This gives quantum computers a theoretical speed advantage. 

Quantum computers use the probability of an object’s state before it’s measured to perform calculations. This means they can process exponentially more data than classical computers. 

Quantum computers can be used for: 

• Simulating chemical reactions 
• Developing new drugs and materials 
• Optimizing systems like traffic flow and financial trading 
• Solving cryptography problems 
• Breaking encryption schemes 
• Performing physical simulations

Quantum computers can be used for many other things, including: 

• Drug discovery and development Quantum computers can simulate chemical systems, such as drug molecules and their interactions with proteins. This could lead to the discovery of new drugs and treatments in a shorter timeframe. 
• Traffic flow Quantum computers can analyze traffic patterns and run simulations to identify the most efficient routes and traffic management strategies. This can reduce congestion and improve transportation efficiency. 
• Cryptography Quantum computers can perform many times more parallel operations than conventional computers. This can break PKC by solving complex mathematical problems or break symmetric key cryptography by exhaustively searching for all possible secret keys. 
• Materials science Quantum computers can simulate molecular structures at the atomic scale. This may have significant applications in batteries, pharmaceuticals, fertilizers and other chemistry-based domains.

Quantum computers are still in development and aren’t widely available. Some quantum computers that exist today include: 

• Osprey: IBM’s 433-qubit computer, which is three times more powerful than its 2021 predecessor. 
• Eagle: IBM’s 127-qubit superconducting quantum computer. 
• Sycamore: Google’s 70-qubit quantum processor. 
• Quantum Brilliance: A diamond-based quantum computer that’s smaller than mainframe quantum computers. 
• D-Wave: A quantum computer that uses quantum annealing for optimization. 

Other types of quantum computers include: 

Superconducting, Photonic, Neutral Atoms, Trapped Ions, Quantum Dots, Topological, Ion trap. 

Some companies building quantum computers include: Microsoft, Alibaba, Honeywell, D-Wave.

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