Quantum mechanics, as currently understood, does not violate conservation laws. Conservation laws are fundamental principles in physics that state certain quantities, such as energy, momentum, and angular momentum, are conserved in isolated systems. These laws are based on the symmetries of the physical laws governing the system.
However, there are cases in which quantum mechanics can appear to violate classical conservation laws, but this is due to the nature of quantum systems and their behavior at the microscopic level. One such example is the phenomenon of quantum tunneling.
Quantum tunneling occurs when a particle with insufficient energy to overcome a potential barrier can still pass through it. In classical physics, a particle with lower energy than the barrier height would be unable to cross it. However, in quantum mechanics, particles exhibit wave-particle duality, and their behavior is described by a wavefunction. This wavefunction allows the particle to "tunnel" through the barrier, effectively appearing on the other side without having classically sufficient energy to do so.
From a conservation perspective, this may seem to violate energy conservation since the particle seemingly "creates" energy to cross the barrier. However, in quantum mechanics, the energy-time uncertainty principle allows for temporary energy fluctuations within a system. These fluctuations are consistent with the conservation of energy over a sufficiently short time interval, as permitted by the uncertainty principle.
In summary, while quantum mechanics may involve behaviors that appear to challenge classical intuitions, it remains consistent with conservation laws at a deeper level, incorporating probabilistic and wave-like characteristics that do not violate the fundamental principles of energy, momentum, and angular momentum conservation.