The choice to develop digital quantum computers instead of analog quantum computers is primarily based on the practical limitations and advantages associated with each approach. Here are a few reasons why digital quantum computers are favored over analog counterparts:
Error correction: Digital quantum computers, based on the principles of quantum error correction, can detect and correct errors that inevitably occur during computation. Error correction is crucial for building reliable and scalable quantum computers. In contrast, analog quantum computers lack built-in error correction mechanisms, making them more susceptible to noise and errors. This makes it challenging to perform complex computations accurately and reliably on analog systems.
Flexibility and universality: Digital quantum computers are inherently more flexible and can be programmed to execute a wide range of algorithms. They employ universal sets of quantum gates to manipulate qubits, allowing for the implementation of various quantum algorithms. Analog quantum computers, on the other hand, are designed to solve specific classes of problems and may not be as versatile or adaptable.
Scalability: Digital quantum computers have a clearer path to scalability. They can be built using standardized qubits and gate operations, allowing for modular and hierarchical approaches to scale up the system. Analog quantum computers, on the other hand, often rely on continuous variables or specific physical systems that may be more challenging to scale up reliably.
Noise resilience: Digital quantum computers are designed to mitigate the effects of noise and decoherence through error correction techniques. By encoding and redundantly protecting quantum information, digital systems can tolerate a certain level of noise and errors. Analog quantum computers, without error correction, are more susceptible to noise, making it difficult to maintain the coherence of the quantum states during computation.
Simulation and control: Digital quantum computers provide better control and measurement capabilities. By performing discrete operations on qubits, digital systems allow for precise control of the quantum states and the ability to measure them accurately. Analog quantum systems, while they can provide continuous evolution of the quantum state, may lack the same level of control and measurement fidelity.
It's important to note that analog quantum systems have their own advantages and may be well-suited for specific applications. For instance, analog quantum simulators can efficiently simulate certain quantum systems or physical processes. However, when it comes to general-purpose quantum computing and addressing the fundamental challenges of error correction, flexibility, and scalability, digital quantum computers have shown more promise and are currently the focus of extensive research and development efforts.