Releases · quantumlib/Qualtran

This preview release of Qualtran contains many improvements and new bloqs.

This is the last planned release before the 1.0 release of Qualtran. 1.0 will bring stronger stability guarantees to the core Qualtran framework: namely everything in the qualtran namespace outside of qualtran.bloqs. The library of bloqs will continue to be extended and edited for greater breadth and accuracy. This development release contains some backwards-incompatible changes to prepare for 1.0. Read on for more information

Bartiq and QREF integration

This release includes interoperability with Bartiq via the QREF format implemented by @mstechly in #1194. Interoperability between quantum algorithms tooling is crucial to accelerate progress in the field.

Qualtran software paper

We've authored a manuscript describing the design of Qualtran, some important algorithmic primitives contained in qualtran.bloqs, and case studies on problems of interest. If you use Qualtran in your own work, please cite:

Expressing and Analyzing Quantum Algorithms with Qualtran. arXiv:2409.04643.

Gate counting and leaf bloqs

We've unified the gate counting framework under the qualtran.resource_counting framework.

The _t_complexity_ annotation is deprecated. Please continue to annotate callees with build_call_graph or use my_static_costs to provide a static override.
The cirq_interop.t_complexity function no longer uses any custom logic. Rather, it goes via qualtran.resource.estimation tools; specifically the QECGatesCost cost key. There should be no observable change to the computed costs. #1313 #1359 #1323 #1333
Toffoli is now an atomic, leaf bloq #1388
CSwap is now an atomic leaf bloq #1393
And will become an atomic leaf bloq #1347
The GraphvizCallGraph.from_bloq helper method can draw call graphs with costs #1254

Tensor simulation overhaul

The tensor simulation protocol was changed to support efficient simulation of a larger class of circuits, including shallow-but-wide circuits. Qualtran can simulate a 2x32-qubit adder using only 6 qubit's worth of RAM for a specific input/output ket following the changes.

Overhaul implemented in #1070. Tensor simulation will always try to flatten as much as possible before starting the contraction. The semantics of my_tensors have changed. If you are overriding this method to support tensor simulation, consider relying directly on the decomposition or read the documentation for full details on how to implement the new method.
Changes to .flatten in #1061. Flattening will no longer raise an error if a bloq doesn't have a decomposition. .flatten() with no arguments will flatten as much as possible.

Physical cost models

The qualtran.surface_code module has been refactored so both Beverland- and Gidney-derived models follow the same interface.

Code changes in #1141 #1154 #1157 #1183 #1185
qualtran.resource_estimation.GateCounts is used directly. AlgorithmSummary and MagicCount dataclasses have been removed as redundant.

Other framework changes

The bit_tools module has been removed and replaced with QDType features by @charlesyuan314 in #1041. Please migrate your code to use QDType methods to convert between bits. New, vectorized from_bits and to_bits by @anurudhp in #1199
Greedy topological sort of the binst graph to minimize qubit allocations / deallocations by @tanujkhattar in #1099
Cirq interop overhaul/bugfixes @tanujkhattar in #1100
QFxp: use integer values for classical sim instead of fxpmath.Fxp by @anurudhp in #1204
Change return type of build_call_graph to set | dict by @dstrain115 in #1356 #1392
pretty_name is deprecated #1340. Use __str__.
Bloq.supports_decompose_bloq has been removed in #1382. Use try/except.
BoundedQUInt has been renamed to BQUInt by @fdmalone in #1363
Better support for symbolics in Signature by @anurudhp in #1353 and @mpharrigan in #1301
param ctrl_spec of get_ctrl_system will always be non-None by @anurudhp in #1209
Zero-bitsize connections are explicitly not allowed by @mpharrigan in #1105

New and updated bloqs

Implement decomposition for BitonicSort by @anurudhp in #1089
Add AutoPartition and BloqBuilder.add_and_partition to fit bloqs together whose registers don't quite match by @charlesyuan314 in #1086
Implement classical action of Cast bloq by @NoureldinYosri in #1093
Add Unitary and TensorProduct block encodings by @charlesyuan314 in #1094
GlobalPhase: use exponent, and implement controlled (ZPowGate) by @anurudhp in #1117
Create ApplyLthBloq as a simple SELECT oracle by @charlesyuan314 in #1107
Add Product block encoding by @charlesyuan314 in #1106
Add Phase block encoding by @charlesyuan314 in #1129
Add LinearCombination block encoding by @charlesyuan314 in #1133
Permutation Bloq by @anurudhp in #1110
Sparse state preparation via alias sampling by @anurudhp in #1067
Implement Negate (two's complement) by @anurudhp in #1144
Add Xor bloq by @charlesyuan314 in #1149
Add InvertRealNumber bloq by @charlesyuan314 in #1151
Add BitwiseNot by @anurudhp in #1161
Add SubtractFrom to subtract from a register in place by @charlesyuan314 in #1158
Switch SubtractFrom to use BitwiseNot by @charlesyuan314 in #1164
Create SparseMatrix block encoding by @charlesyuan314 in #1143
Optimize gate count of Subtract to n-1 Toffolis by @NoureldinYosri in #1057
CHadamard by @mpharrigan in #1114
CYGate by @mpharrigan in #1115
CZ by @mpharrigan in #1116
Disallow zero sized registers in QROMs and PRGAViaPhaseGradient by @tanujkhattar in #1160
Add ExplicitEntryOracle to block encode a matrix by @charlesyuan314 in #1166
ControlledAddOrSubtract Bloq by @anurudhp in #1145
Update classical action of addition gates and fix classical action bug in Join by @NoureldinYosri in #1174
Implement generic MultiControlledBloq using single-controlled subbloq + And ladder. by @anurudhp in #1155
ControlledViaAnd tests and bloq examples by @anurudhp in #1182
Add SignExtend for two's complement sign extension by @anurudhp in #1162
Add SymmetricBanded matrix block encoding by @charlesyuan314 in #1177
Add ArcSin bloq by @charlesyuan314 in #1188
Add symbolic call graph for SparseMatrix by @charlesyuan314 in #1193
Revamp ChebyshevPolynomial by @charlesyuan314 in #1213
Bitwise bloqs are self adjoint by @anurudhp in #1220
Update QROAM in chemistry prepare bloqs to use clean ancilla by @fdmalone in #1226
Add ScaledChebyshevPolynomial bloq by @charlesyuan314 in #1231
Add an optimizer for LinearCombinations by @charlesyuan314 in #1232
Add FFT QSP by @Epsilon1024 in #1078
RzViaPhaseG...