There are several reasons why portable quantum computers are not yet a reality:
Technical Challenges: Building a quantum computer is an extremely complex task. Quantum systems are highly sensitive to their environment, and even small disturbances can cause errors and decoherence, which can lead to the loss of quantum information. Achieving the level of control required to maintain the delicate quantum states of qubits in a portable and robust device is a significant technical challenge.
Qubit Scalability: Quantum computers require a large number of qubits to perform meaningful computations that surpass classical capabilities. Currently, the number of qubits in existing quantum computers is limited, ranging from a few to a few hundred. Scaling up the number of qubits while maintaining their coherence and reliability is a major hurdle that researchers are actively working on.
Error Correction: Quantum systems are prone to errors due to noise, imperfections, and interactions with the environment. To overcome these errors, error correction techniques need to be implemented. However, error correction in quantum computing is still an ongoing area of research, and developing efficient error correction codes that can mitigate errors and extend the lifespan of quantum information is crucial before portable quantum computers can become a reality.
Cooling and Control Requirements: Quantum computers require extremely low temperatures to reduce thermal noise and maintain the delicate quantum states of qubits. Many existing quantum computers operate at temperatures near absolute zero (-273.15 degrees Celsius). Achieving and maintaining such low temperatures in a portable device presents significant challenges in terms of power consumption, heat dissipation, and overall device size.
Size and Infrastructure: Current quantum computers are large and require specialized infrastructure, such as precise control systems, shielding from external interference, and elaborate cooling setups. Miniaturizing and integrating these components into a portable form factor while maintaining their functionality and performance is a complex engineering task.
While progress is being made in all these areas, it will likely take time and continued advancements in technology and engineering to overcome these challenges and develop portable quantum computers that can be easily transported and used outside of specialized laboratory environments.