if you're referring to a quantum computer i think its that the device is being constantly powered by an electric power supplyoknow said:TL;DR Summary: on the source of qubit superpositions
When I observe a qubit's state, decoherence happens such that I find the qubit in a particular state. After I cease observing a qubit's state, what physical process causes a fresh superposition of states to develop? Is zero-point energy at least a contributor?
Why do you think a fresh superposition develops?oknow said:After I cease observing a qubit's state, what physical process causes a fresh superposition of states to develop?
Why would you believe that? A qubit doesn't have to start out in a superposition to be useful for a computation. Indeed, usually you don't want it to start out in a superposition, because you want to be able to control exactly which other qubits it's entangled with and in what manner. That means you want to know what state it starts out in.oknow said:Since such qubits are generally reusable for additional computations, I believe a fresh superposition must develop at some point after observation ceases.
The answer in general must be quantum computer engineering. Controlling the state of the quibits generally is what QC is all about. In the same way that a classical computer must be able to set its bits and bytes to certain values.oknow said:Yes, I'm thinking quantum computing qubits. Since such qubits are generally reusable for additional computations, I believe a fresh superposition must develop at some point after observation ceases. I am curious when that superposition refresh, if you will, is thought to happen, and by what process.
One answer is that no process is needed: Your newly observed qubit is already in a superposition. Recall that whether or not a state is a superposition, depends on your chosen basis. So when your qubit is in state |0> or |1>, it is also in a superposition, e.g. of |+> and |->.oknow said:When I observe a qubit's state, decoherence happens such that I find the qubit in a particular state. After I cease observing a qubit's state, what physical process causes a fresh superposition of states to develop? Is zero-point energy at least a contributor?
That is not -generally speaking- what would happen. As has already mentioned we typically want out qubit to be in a known state at the beginning of a computation; and in nearly all cases this will be the qubit ground state. Unless you are using some sort of active reset (which is different topic) many real computations start by waiting "long enough" (something like 5 times the relaxation time) so that we can be reasonably sure that the qubits are in their ground state (aka zero state). The operations that put the qubits into superpositions (or e.g. entangle multiple qubits) are always part of the circuit itself'.oknow said:Yes, I'm thinking quantum computing qubits. Since such qubits are generally reusable for additional computations, I believe a fresh superposition must develop at some point after observation ceases. I am curious when that superposition refresh, if you will, is thought to happen, and by what process.
This post reveals that you haven't understood the basics of states (pure and mixed) and superposition of states. Moreover, system evolution over time is driven by the Hamiltonian.oknow said:I'll check out the references mentioned, thanks.
I'm wondering about the source of a fresh superposition at a more fundamental level than, say, other circuitry, electricity supply, gates, etc. Yes, in my example the qubit starts at a known state because I just observed it. Assume at that point, while observing the qubit's state, I severe its connection with other circuitry, then I stop observing at it. Does that qubit then remain forever in the last state I observed, or does a fresh superposition along the same basis arise? If the latter, what fundamental physics triggers that fresh uncertainty of state?
A qubit superposition is a quantum state that is a combination of two or more states. This allows the qubit to exist in multiple states simultaneously, unlike classical bits which can only exist in one state at a time.
Qubit superpositions are formed through a process called quantum superposition. This occurs when a qubit is in a state of quantum uncertainty, meaning it has not yet been measured or observed. The qubit can exist in a combination of states until it is measured, at which point it collapses into a single state.
Qubit superpositions are primarily caused by the principles of quantum mechanics, specifically the concept of superposition. This allows particles to exist in multiple states at once, and when applied to qubits, it allows them to be in multiple states simultaneously.
Yes, qubit superpositions can be controlled through a process called quantum manipulation. This involves applying external forces or fields to the qubit to manipulate its state and create specific superpositions. This is a crucial aspect of quantum computing and allows for the creation of complex algorithms and computations.
Qubit superpositions are significant because they are the foundation of quantum computing. They allow for the creation of powerful algorithms and computations that are not possible with classical computers. Qubit superpositions also have potential applications in fields such as cryptography, drug discovery, and artificial intelligence.