en:this_little_thing_called_qubit
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en:this_little_thing_called_qubit [2021/01/09 19:15] jaddawyn |
en:this_little_thing_called_qubit [2021/01/16 10:29] (current) |
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| - | ====== This little thing called | + | ====== This little thing called |
| - | qbit stands for " | + | qubit (or qubit) |
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| ===== What is a bit ? ===== | ===== What is a bit ? ===== | ||
| - | A bit is used in classical computation to carry information. It is an electrical state with two levels, for instance 1 Volt and 4 Volts. At each state is associated a numeric value: 0 or 1. This is the basic of numeric system.\\ | + | A bit is used in classical computation to carry information. It is an electrical state with two levels, for instance 1 Volt and 4 Volts. At each state is associated a numeric value: 0 or 1. This is the basic of binary |
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| In computers, classical microprocessors are running billions of operations using bits every second. \\ | In computers, classical microprocessors are running billions of operations using bits every second. \\ | ||
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| **0 0 0 0 0 1 1 1** | **0 0 0 0 0 1 1 1** | ||
| ;#; | ;#; | ||
| - | I won't explain how to encode and decode values from mathematical value to binary value, someone else already did that better:\\ | + | I won't explain how to encode and decode values from mathematical value to binary value, someone else already did that right:\\ |
| - | XXX\\ | + | ;#; |
| + | [[https:// | ||
| + | ;#; | ||
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| You'll need to be ease with this to understand what follows. | You'll need to be ease with this to understand what follows. | ||
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| + | ==== What is a qubit ? ==== | ||
| + | Classic bits are based on voltage associated to binary level 0 or 1, while qubits are based on quantum states.\\ | ||
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| + | A qubit is a particle and has 2 base states noted |0> and |1> (called Dirac notation, we'll see that in detail later). As a quantum particle, it is in superposed state before being read. Like the cat that is both dead and alive before you open the box.\\ | ||
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| + | Let's come back to the previous experiment: | ||
| + | {{ : | ||
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| + | When the particle leaves the source it is in superposed state: i.e. a probability combination of |0> and |1>. When it comes to the detector, decoherence happens and the particle collapses to a fixed state |0> or |1>. | ||
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| + | But manipulating qubits alone is quite useless. But the same way we can group bits into sets, qubits can be grouped into **registers**.\\ | ||
| + | A quantum register is a set of several qubits we will use for computing. | ||
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| + | You must wonder what is the point of qubits since we get 0 or 1 in the end like bits... all is about probabilities in the middle. Be patient we'll see that later. | ||
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| + | <columns 100% 50% -> | ||
| + | Previous: [[en: | ||
| + | < | ||
| + | ;;# | ||
| + | Next: [[en: | ||
| + | ;;# | ||
| + | </ | ||
en/this_little_thing_called_qubit.1610216108.txt.gz · Last modified: 2021/01/16 10:29 (external edit)
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