Quantum computers operate based on the principles of quantum mechanics, which involve delicate quantum states and superposition. To maintain and manipulate these fragile quantum states, quantum computers need to be isolated from external disturbances, especially thermal fluctuations. This is why low temperatures are necessary for quantum computers to function effectively.
When a system is cooled to very low temperatures, such as near absolute zero (0 Kelvin or -273.15 degrees Celsius), the thermal energy of the system decreases significantly. This reduction in thermal energy helps minimize the effects of thermal noise and decoherence, which can disrupt the fragile quantum states that quantum computers rely on for computation.
Quantum systems are susceptible to interactions with their surrounding environment, which can introduce errors and cause loss of coherence. By cooling the system, the thermal fluctuations of the environment are reduced, leading to a more stable and controllable quantum state. This allows quantum computers to maintain coherent superpositions and perform quantum operations with higher fidelity.
Different quantum computing technologies have different temperature requirements. For example, superconducting qubits, one of the leading platforms for building quantum computers, often require extremely low temperatures in the millikelvin range (near absolute zero). Other technologies, such as trapped ions or topological qubits, may have different temperature requirements but still need to be cooled significantly to minimize environmental disturbances.
While low temperatures are crucial for maintaining the delicate quantum states in a quantum computer, it's important to note that not all components of a quantum computer need to be at ultra-low temperatures. Typically, only the qubits, the fundamental building blocks of quantum information, require such extreme cooling, while other parts of the system, such as control electronics, can operate at higher temperatures.