Quantum computers are susceptible to the external environment due to a phenomenon called quantum decoherence. Decoherence refers to the loss of quantum coherence, which is the delicate property that allows quantum systems to exist in superposition and exhibit entanglement.
Several factors contribute to the susceptibility of quantum computers to the external environment:
Interaction with surrounding particles: Quantum systems can interact with particles in their surrounding environment, such as air molecules or impurities in materials. These interactions can disrupt the delicate quantum state of the qubits, leading to decoherence. The more qubits a quantum computer has, the more opportunities there are for these interactions to occur, making it challenging to maintain the coherence of the system.
Thermal effects: Quantum systems are sensitive to temperature fluctuations. Even small variations in temperature can cause qubits to lose coherence. As the temperature increases, the system becomes more chaotic, and quantum effects become harder to control. Cooling the quantum computer to extremely low temperatures, such as near absolute zero, helps mitigate this issue but is still not completely immune to thermal effects.
Magnetic fields and electromagnetic radiation: Magnetic fields and electromagnetic radiation from the environment can interfere with the precise control of qubits. These external fields can induce random fluctuations in the quantum states of the qubits, leading to errors in computations. Shielding the quantum computer from external electromagnetic influences can help minimize this interference.
Imperfections in hardware and materials: Manufacturing and operational imperfections in the physical components of quantum computers, such as qubits and control systems, can introduce errors and noise into the system. These imperfections can arise from defects in materials, limitations in fabrication techniques, or challenges in maintaining precise control over qubit states.
Overcoming these challenges is an active area of research in the field of quantum computing. Scientists and engineers are developing techniques such as error correction codes, improved qubit designs, and better environmental shielding to mitigate the effects of decoherence and enhance the stability of quantum systems. These efforts aim to improve the robustness of quantum computers and make them more resilient to external influences.