Limitations of Quantum Computing

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

• Interference. The slightest disturbance in a quantum system can cause a quantum computation to collapse a process known as decoherence. A quantum computer must be totally isolated from all external interference during the computation phase. Some success has been achieved with the use of qubits in intense magnetic fields.

• Error correction. Qubits aren't digital bits of data and can't use conventional error correction. Error correction is critical in quantum computing, where even a single error in a calculation can cause the validity of the entire computation to collapse. There has been considerable progress in this area, however, with an error correction algorithm developed that uses 9 qubits -- 1 computational and 8 correctional. A system from IBM can make do with a total of 5 qubits -- 1 computational and 4 correctional.

• Output observance. Retrieving output data after a quantum calculation is complete risks corrupting the data. Developments such as database search algorithms that rely on the special wave shape of the probability curve in quantum computers can avoid this issue. This ensures that once all calculations are performed, the act of measurement sees the quantum state decohere into the correct answer.

• Security.  Security and quantum cryptography is not yet fully developed.

• lack of qubits. A lack of qubits prevents quantum computers from living up to their potential for impactful use. Researchers have yet to produce more than 128.