1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
use super::{GateOp, QuantumGate, QuantumRegister, QuantumState};
use crate::gates::*;
use crate::maths::vector::Vector;
use crate::{complex, Complex, Matrix};
use rayon::prelude::*;
/// Minimum number of qubits to enable parallelism (2^8 = 256 state vector elements)
const PARALLEL_THRESHOLD: usize = 8;
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum Runtime {
#[default]
BasicRT,
BasicRTMT,
WFEvolution,
WFEvolutionMT,
GPUAccelerated,
}
impl Runtime {
pub fn compute(&self, num_qubits: usize, operations: &[GateOp]) -> QuantumState {
match self {
Runtime::BasicRT => Self::compute_basic(num_qubits, operations),
Runtime::BasicRTMT => Self::compute_basic_mt(num_qubits, operations),
Runtime::WFEvolution => {
unimplemented!("WFEvolution (Schrödinger equation) runtime not yet implemented")
}
Runtime::WFEvolutionMT => {
unimplemented!(
"WFEvolutionMT (multi-threaded Schrödinger) runtime not yet implemented"
)
}
Runtime::GPUAccelerated => {
unimplemented!("GPUAccelerated runtime not yet implemented")
}
}
}
fn compute_basic(num_qubits: usize, operations: &[GateOp]) -> QuantumState {
let names: Vec<String> = (0..num_qubits).map(|i| format!("q{}", i)).collect();
let leaked_names: &'static [String] = Box::leak(names.into_boxed_slice());
let name_refs: Vec<&'static str> = leaked_names.iter().map(|s| s.as_str()).collect();
let mut register = QuantumRegister::new(
Box::leak(Box::new("circuit".to_string())).as_str(),
&name_refs,
);
for op in operations {
match op {
GateOp::H(t) => register.apply_gate(&HADAMARD, &[*t]),
GateOp::X(t) => register.apply_gate(&PAULI_X, &[*t]),
GateOp::Y(t) => register.apply_gate(&PAULI_Y, &[*t]),
GateOp::Z(t) => register.apply_gate(&PAULI_Z, &[*t]),
GateOp::S(t) => register.apply_gate(&S_GATE, &[*t]),
GateOp::T(t) => register.apply_gate(&T_GATE, &[*t]),
GateOp::CNOT(c, t) => register.apply_gate(&CNOT, &[*c, *t]),
GateOp::CZ(c, t) => register.apply_gate(&CZ, &[*c, *t]),
GateOp::SWAP(a, b) => register.apply_gate(&SWAP, &[*a, *b]),
GateOp::CCNOT(c1, c2, t) => register.apply_gate(&TOFFOLI, &[*c1, *c2, *t]),
GateOp::CSWAP(c, t1, t2) => register.apply_gate(&FREDKIN, &[*c, *t1, *t2]),
GateOp::Measure(_, _) => {}
GateOp::Custom(gate, targets) => {
let quantum_gate = gate.to_quantum_gate();
register.apply_gate(&quantum_gate, targets);
}
}
}
register.get_state()
}
fn compute_basic_mt(num_qubits: usize, operations: &[GateOp]) -> QuantumState {
// For small circuits, fall back to single-threaded (overhead not worth it)
if num_qubits < PARALLEL_THRESHOLD {
return Self::compute_basic(num_qubits, operations);
}
let dim = 1 << num_qubits;
// Initialize state to |0...0⟩
let mut state: Vec<Complex<f64>> = vec![complex!(0.0, 0.0); dim];
state[0] = complex!(1.0, 0.0);
for op in operations {
let (gate, targets): (&QuantumGate, Vec<usize>) = match op {
GateOp::H(t) => (&HADAMARD, vec![*t]),
GateOp::X(t) => (&PAULI_X, vec![*t]),
GateOp::Y(t) => (&PAULI_Y, vec![*t]),
GateOp::Z(t) => (&PAULI_Z, vec![*t]),
GateOp::S(t) => (&S_GATE, vec![*t]),
GateOp::T(t) => (&T_GATE, vec![*t]),
GateOp::CNOT(c, t) => (&CNOT, vec![*c, *t]),
GateOp::CZ(c, t) => (&CZ, vec![*c, *t]),
GateOp::SWAP(a, b) => (&SWAP, vec![*a, *b]),
GateOp::CCNOT(c1, c2, t) => (&TOFFOLI, vec![*c1, *c2, *t]),
GateOp::CSWAP(c, t1, t2) => (&FREDKIN, vec![*c, *t1, *t2]),
GateOp::Measure(_, _) => continue,
GateOp::Custom(custom_gate, tgts) => {
let quantum_gate = custom_gate.to_quantum_gate();
state = apply_gate_parallel(&state, &quantum_gate.matrix, tgts, num_qubits);
continue;
}
};
state = apply_gate_parallel(&state, &gate.matrix, &targets, num_qubits);
}
QuantumState::new(state)
}
}
/// Apply a gate to the state vector in parallel using sparse application
/// This is O(2^n * 2^g) instead of O(2^2n) for full matrix multiplication
fn apply_gate_parallel(
state: &[Complex<f64>],
gate_matrix: &Matrix<Complex<f64>>,
targets: &[usize],
num_qubits: usize,
) -> Vec<Complex<f64>> {
let dim = 1 << num_qubits;
let g = targets.len();
let gate_dim = 1 << g;
// Convert target qubit indices to bit positions (from MSB)
let target_bits: Vec<usize> = targets.iter().map(|&t| num_qubits - 1 - t).collect();
// Create a mask for non-target qubits
let mut non_target_mask: usize = (1 << num_qubits) - 1;
for &pos in &target_bits {
non_target_mask &= !(1 << pos);
}
// Parallel computation of new state
let new_state: Vec<Complex<f64>> = (0..dim)
.into_par_iter()
.map(|i| {
// Extract the target qubit bits from index i
let mut target_idx = 0usize;
for (k, &pos) in target_bits.iter().enumerate() {
if (i >> pos) & 1 == 1 {
target_idx |= 1 << (g - 1 - k);
}
}
// Compute the contribution to state[i]
let mut sum = complex!(0.0, 0.0);
// For each possible input state that could contribute
for j in 0..gate_dim {
// Get the gate matrix element
let gate_elem = gate_matrix.data[target_idx * gate_dim + j];
// Skip if zero (sparse optimization)
if gate_elem.real.abs() < 1e-15 && gate_elem.imaginary.abs() < 1e-15 {
continue;
}
// Compute the source index by replacing target bits in i with bits from j
let mut source_idx = i & non_target_mask;
for (k, &pos) in target_bits.iter().enumerate() {
if (j >> (g - 1 - k)) & 1 == 1 {
source_idx |= 1 << pos;
}
}
sum = sum + gate_elem * state[source_idx];
}
sum
})
.collect();
new_state
}
|
