Using leptons, such as electrons, as the fundamental building blocks for quantum computing comes with a few disadvantages. Here are some of them:
Decoherence: Leptons, like other physical systems, are susceptible to decoherence. Decoherence refers to the loss of quantum coherence, which occurs when quantum states interact with their surrounding environment, leading to the destruction of delicate quantum information. Leptons can interact with their environment through various channels, such as electromagnetic fields, phonons, or other particles, causing unwanted noise and errors in quantum computations.
Fragility: Leptons are sensitive to external influences, making them fragile for quantum computation purposes. They can be easily affected by temperature variations, electromagnetic fields, and other forms of interference, leading to errors and inaccuracies in quantum operations. Maintaining the required level of isolation and control to protect leptons from external influences can be technically challenging.
Scalability: Leptons are individual particles, and manipulating them individually for large-scale quantum computing can be difficult. As the number of qubits increases, the complexity of controlling and interconnecting individual leptons grows exponentially. This poses challenges for scaling up quantum computers to a level where they can outperform classical computers for complex computational tasks.
Interactions: Leptons interact with other particles and electromagnetic fields, making it challenging to implement long-range interactions needed for certain quantum algorithms. Designing and engineering systems that enable the controlled interaction of leptons over long distances can be technically demanding.
Readout and measurement: Extracting information from individual leptons without disturbing their quantum states can be problematic. Performing accurate and non-destructive measurements on qubits is crucial for obtaining reliable results. However, achieving high-fidelity readout of individual leptons can be challenging due to their small size and the limitations of measurement techniques.
It's worth noting that despite these disadvantages, leptons have also been extensively studied and used in various quantum computing architectures. Researchers are actively exploring ways to mitigate these challenges through error correction techniques, improved control and measurement methods, and novel qubit designs. Additionally, alternative approaches, such as using other types of quantum systems (e.g., superconducting circuits, trapped ions, topological qubits), are also being pursued to overcome some of the limitations associated with leptons.