In a quantum computer, the qubits, not cubits, are the fundamental units of information and are indeed susceptible to entanglement with other particles in the environment. When two or more qubits become entangled, their quantum states become correlated in a way that cannot be described independently for each qubit.
The spin properties, or more accurately, the quantum states of qubits, do not necessarily have to match or be in common with the particles they entangle with. In fact, entanglement can occur between qubits with different spin properties or even between qubits and other types of quantum degrees of freedom, such as photon polarizations.
Entanglement arises from the interaction between quantum systems, and the specific details of the entanglement depend on the nature of the interaction. When two quantum systems interact, their states become entangled, and measuring the state of one qubit will instantaneously affect the state of the other, regardless of their spin properties. This non-local correlation is a key feature of entanglement and plays a crucial role in quantum information processing.
However, it is important to note that in practical quantum computing implementations, maintaining and controlling entanglement is a significant challenge due to the fragile nature of quantum states and their susceptibility to environmental disturbances. Strategies such as error correction techniques and decoherence mitigation methods are employed to mitigate the effects of entanglement loss or degradation in quantum computers.